YouTube’s server-side ad insertion makes ad blocking more complicated
YouTube has come up with a new tactic to thwart ad blockers: embedding advertisements directly into the video content itself via a method called server-side ad insertion. This approach significantly complicates the task of ad blockers to detect and block ads. While there is no out-of-the-box solution to this problem, we are currently investigating ways to combat this new tactic and remain optimistic that we will be able to overcome this hurdle in the future.
How it started
YouTube has been ramping up its war on ad blockers for about a year now. Initially, it experimented with pop-up messages informing users that “ad blockers are not allowed on YouTube.” Then, the Google-owned platform began testing a three-strikes policy, warning viewers that the video would stop playing after three videos unless they disabled their extensions. Some warnings even included a countdown clock up to 60 seconds long, showing users how much time they had left to “allow YouTube ads” or “try YouTube Premium” before seeing the message again.
Co-founder and CTO of Adguard.
How it goes: a new escalation
During this time, adblockers have held their ground and largely adapted to YouTube’s adblocker blocking methods. Adblockers and YouTube have been locked in a never-ending tug-of-war, with neither side achieving a definitive victory.
Now, YouTube appears to have upped the ante in the ongoing battle by revealing what it hopes will be its trump card. As first reported by 9to5Google, YouTube has been spotted using a method known as server-side ad injection. We’re already seeing backlash from other ad-blocking extension developers.
For example, the developer of the crowdsourced ad blocking extension SponsorBlock has announced that the extension will not work for users involved in this experiment in the short term (as server-side ad injection appears to be a limited test for now).
The AdGuard team has also observed the new ad insertion method. How does it work and how does it differ from what YouTube did before?
Server-side ad insertion: not entirely new
Server-side ad insertion differs from normal YouTube ad insertion techniques primarily in how ads are delivered to viewers. With traditional methods, ads are displayed separately from the video content, allowing ad blockers to intercept and block them. However, with server-side ad injection, the ad is incorporated into the video stream itself, making it indistinguishable from the content. This makes ad blockers less effective as they cannot distinguish between ads and the actual video.
While YouTube hasn’t previously used this method on the web, it uses a strikingly similar tactic in its mobile apps. To dig a little deeper into the technical details, YouTube uses the UMP protocol to load video metadata, ad metadata, and the videos themselves in requests to *.googlevideo.com. This domain, operated by Google, serves as a platform for hosting and delivering various types of video content across Google’s services, including YouTube.
The similarity between this protocol and YouTube’s new ad insertion tactics lies in the approach to data bundling and delivery. Just as server-side ad insertion integrates ads directly into the video content, UMP packages video and ad metadata, ads, and the content itself into a streamlined format.
What does this mean for adblockers?
In a nutshell, the new ad insertion tactics spell more trouble for ad blockers. It hampers ad blockers’ ability to effectively filter ads from the responses YouTube sends to your device’s requests to play a video. Ad blocking extensions are particularly vulnerable to these tactics compared to desktop ad blocking applications, as they have fewer resources to counter this method.
There is currently no watertight solution to this problem, but that certainly does not mean that it will not arise in the future. Filter developers are already working on short-term solutions and are actively looking for a more stable solution.
Clutch!
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