Display and video are the two formats most programmatic buyers start with, and for good reason: both are available at large scale through the open market, both can be bought through the same DSP, and they do different jobs well. The mistake many advertisers make is treating them as interchangeable, or picking one and ignoring the other. This guide explains how each format is bought and measured, where each fits in a campaign, and how to plan them together.
How display and video are bought programmatically
Both formats travel through the same basic chain. A publisher makes ad space available through an SSP or ad exchange. When a user loads the page, app or video player, the SSP sends a bid request, usually following the IAB Tech Lab’s OpenRTB protocol, to connected DSPs. Each DSP decides whether to bid and how much, the highest eligible bid wins, and the winning ad is delivered.
The difference is in what gets delivered:
- Display creatives are images (JPG, PNG, GIF) or HTML5 banners, plus native ads assembled from a headline, image and text that match the look of the site.
- Video creatives are usually delivered through a VAST tag: an XML document that tells the video player where the media file is, how long it is and which tracking URLs to call at each stage of playback. If VAST is new to you, our guide to VAST, VPAID and video ad serving walks through it step by step.
Display advertising: what it is good at
Display covers standard banner sizes, interstitials and native units on websites and apps. Its strengths are practical:
- Scale. Almost every ad-supported site and app has display slots, so reach is wide in most markets.
- Cost. Display impressions are typically cheaper than video, which makes it suitable for testing audiences, offers and messages.
- Retargeting. Display is the usual workhorse for reminding people who visited your site or added items to a cart.
- Simple production. A set of static banners in a few sizes can be made quickly, and changes are cheap.
Its weaknesses are just as real. Banners are easy to ignore, and a share of display impressions are never actually seen because they load below the fold or in cluttered layouts. This is why viewability matters (see below).
Native ads deserve a separate note. Because they match the surrounding content, they tend to feel less intrusive than banners, but they must still be clearly labelled as advertising. Test native and standard banners as separate line items, since their click behavior and costs usually differ, and judge each by conversions rather than by clicks alone.
Video advertising: what it is good at
Video combines sound, motion and story, so it can explain a product or build a brand impression in a way a banner cannot. In programmatic, video comes in two broad types.
In-stream video
In-stream ads play inside a video player around content the user chose to watch: pre-roll (before), mid-roll (during) and post-roll (after). The user expects video and usually has sound on, so attention tends to be higher. Inventory is more limited and more expensive.
Outstream video
Outstream ads play outside of video content, for example in a player that opens between paragraphs of an article or inside a feed. They add video reach on sites that have no video content of their own. They usually start muted and depend on the user scrolling past, so creative must work without sound and should get its message across early.
Connected TV and apps
Video is also sold programmatically in mobile apps and on connected TV (CTV) and OTT services. Screens, viewing habits and measurement differ by environment, so it is worth reporting them separately rather than blending them with desktop web video.
Display vs video at a glance
| Display | Video | |
|---|---|---|
| Typical role | Reach, retargeting, direct response | Awareness, consideration, storytelling |
| Creative formats | Image, HTML5, native | MP4 and other media via VAST tags |
| Relative cost | Lower | Higher |
| Production effort | Low | Medium to high |
| Key quality metric | Viewability | Viewability and completion rate |
| Common pricing | CPM, CPC, CPA goals | CPM, cost per completed view |
Metrics that actually matter
Viewability
An impression is counted when the ad is served, not necessarily when it is seen. Viewability measures whether the ad had a real chance to be seen. The widely used industry standard from the MRC and IAB counts a display ad as viewable when at least half of its pixels are on screen for at least one continuous second, and a video ad when at least half is on screen for two continuous seconds. Buying with a viewability threshold costs more per impression but often less per ad actually seen.
Completion rate
For video, completion rate is the share of started ads that played to the end. It tells you about both creative and placement: low completion can mean the ad is too long, the opening is weak, or the placement is poor (for example tiny autoplay players). Look at quartile reports (25%, 50%, 75%, 100%) to see where viewers drop off.
Clicks and conversions
Click-through rate is useful for display but a weak guide for video, where many people watch and act later. For video, pair view metrics with post-view conversions or brand lift studies where available.
How to combine them in one plan
The most effective setups use each format for what it does best and connect them with audiences:
- Introduce with video. Run in-stream or outstream video to a broad but relevant audience to explain what you offer.
- Build an audience from engagement. Collect users who watched a meaningful part of the video or visited your site.
- Follow up with display. Retarget those users with display and native ads that carry a clear offer and call to action.
- Control repetition. Apply frequency caps across both formats so the same user is not overloaded.
- Schedule sensibly. Use dayparting where your audience or sales team has clear active hours.
- Measure the whole path. Judge video partly by what it does for display conversions, not only by its own clicks.
Pre-launch checklist
- Display creatives in the main IAB sizes your inventory needs, under the file size limits of your DSP.
- Video files in common resolutions and aspect ratios, with captions or on-screen text for muted playback.
- VAST tags tested in a validator before upload.
- Conversion tracking and audience pixels installed and firing.
- Brand safety and fraud filters switched on.
- Separate reporting lines for in-stream, outstream, app and CTV.
Common mistakes
- Repurposing a TV spot as outstream without edits. Outstream usually plays muted in a small player, so a slow, sound-led opening is lost.
- Judging video on click-through rate. It undervalues video’s role earlier in the funnel.
- Ignoring viewability. Cheap display impressions can be cheap because nobody sees them.
- Blending all video inventory in one line item. In-stream, outstream and CTV perform differently and should be priced and judged separately.
- No cross-format frequency cap. Users see the same brand repeatedly across formats and tune out.
- Uploading untested VAST tags. Broken tags waste spend and lose tracking data.
FAQ
Should a small advertiser start with display or video?
Usually display, because creative is cheaper and testing is faster. Add video once you know which audiences and messages work, or earlier if your product needs explaining.
Is outstream video worth buying?
It can be, as a lower-cost way to add video reach. Buy it with viewability and completion targets, and design the creative to work without sound.
What is the difference between VAST and VPAID?
VAST describes which video to play and what to track. VPAID added interactive code inside the ad, but it has been largely replaced by newer standards such as SIMID and OMID for interactivity and measurement. Our video ad serving guide covers this in detail.
Can I run both formats in one DSP?
Most DSPs support both. Running them in one platform makes shared audiences, frequency caps and reporting much easier.
Final thoughts
Display gives you reach and an efficient way to follow up. Video gives you attention and a way to tell a story. Programmatic buying lets you plan both with one set of audiences, caps and reports. Treat them as two parts of one plan, measure each by the job it is meant to do, and adjust the mix as data comes in.
AdTech Europe offers self-serve or managed access to display and video inventory across websites, apps and CTV, with support for HTML5, MP4 and VAST creatives, if you want to put this into practice in one place.
