How Does Video Ad Serving Work?

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  • Post last modified:April 23, 2020

How does video ad serving work and what factors make the best video ad server?

Video advertising is one of the most effective ad formats used in display advertising. Even more so, on mobile platforms as consumers are spending more time, consuming content and watching video adverts on their mobile devices.

As an advertiser, you need to understand how video ad serving works and the different types of video ad formats available.

Video ad serving works the same as ad serving, where an ad creative is ‘served’ from an ad server into multiple websites or applications. There are two types of ad servers – the advertiser ad server and the publisher ad server.

The best video ad serving platforms follow the IAB standards, using an XML specification called VAST. It allows video ads to be served into any online video player on different platforms (mobile & desktop, web & app) that supports VAST. Put bluntly, VAST allows video players and ad servers to speak the same language.

There are two types of tags that a video ad server should be able to generate, a VAST and VPAID tag. This tag is passed on to different publishers and tracking is done across them.

The difference with VPAID is that it allows ads to have more interactive features. It also allows video ad servers to track more advanced measurement, around ad viewability.

Types Of Online Video Ads

There are several types of video ads, each with their strengths and weaknesses. There is no one single best video ad format, but rather, as an advertiser, you should pick certain ad formats depending on the KPIs of your ad campaign.

We’ll briefly introduce and explain the different types of video ads.

In-Stream Video Ad

How Does Video Ad Serving Work? 1

The most common type of video ad that most are familiar with. In-stream video ads are ads that play within the video player – before, during or after a video content.

Advertisers call these ads the pre-roll, mid-roll and post-roll ads. They are also known as linear ads as they play inline with the video content.

Following the IAB standards, these ads are usually 15 to 30 seconds in length. They can be shorter but is rarely any longer than 30 seconds.

Pre-Roll Video Ad

A pre-roll video ad plays before the content. It is usually non-skippable thus making the ad attention-grabbing, but because of this, could cause a negative brand impact – if not implemented correctly.

Mid-Roll Video Ad

Mid-roll video ads are ads that play in between content. The video content gets paused when a mid-roll ad plays and continues once the ad complete. Mid-roll video ads get very low abandonment rates, as the viewer is already invested in watching the video content. However, on the downside, they are quite intrusive.

Post-Roll Video Ad

Post-roll ads are ads that play upon the end of video content. They are non-intrusive but often get higher abandonment rates, as the viewer has already reached the end of the content and has no need to stick around.


Out-Stream Video Ad

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Out-stream video ads are ads that run out of a video player or video content. It runs just like a display banner and can be served as a display banner ad between website content or in-app.

Out-stream video ads can also be made to autoplay in a muted state, upon being scrolled into view and upon tapping or mousing over, the audio turns on.

There are a few advantages to running out-stream video ads:

  1. They do not need to be constrained to video content. This means they can be served into more ad inventories, including premium placements.
  2. They are less intrusive as they do not interfere with video content.
  3. They blend within website content and encourage more engagement.

Out-stream video ads are found to have a 2.5% higher clickthrough rate compared to in-stream ads.

How Does Video Ad Serving Work? 3


How To Choose The Best Video Ad Server for Your Campaigns

Ad serving is actually pretty complex. It all depends on the type of ads  (display, interactive or video), the ad platform (desktop, mobile phone, tablet, etc.) and whether the ad is served through a programmatic platform or through direct buys.

Third-party video ad servers simplify this process, acting as a platform where you simply upload video files and it takes care of the conversion, size compression, and platform compatibility.

Tracking and reporting capability are also important features a video ad server must have. Tracking functions are done with a VAST Wrapper, whereby data points from interactions, impressions, viewability, and clicks on the ad are recorded and reported on the video ad server.

A video ad server usually tracks:

  1. Video play measurement – Start rate, video percentile play, completion rate, etc.
  2. Interaction events – Mute, un-mute, resume, rewind, fullscreen, etc.
  3. Ad viewability
  4. Ad block tracking

MobileAds is a mobile video advertising platform with detailed analytics. Should you need more information about Video Ad Serving, reach out by email us @ now!


Alvin is the Founder and CEO of He is a go-getter, and adventurous guy who believes in working smart to gain success in his business ventures and in life. He also founded and

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