Video revenue is already under pressure for many publishers, and for some, there’s an additional risk approaching. At the end of April, a change in how Prebid video ads are served through Google Ad Manager may cause video ads to fail. This can happen even when there is demand for them.
This isn’t a market shift or a buyer pullback. It’s a technical change in the programmatic plumbing, and for publishers relying on Prebid video, it’s important to understand what’s changing and what action is required.
What’s Actually Changing
Today, when a video ad wins a Prebid auction and is passed into Google Ad Manager (GAM), there’s a brief moment where the video file needs to be temporarily stored while GAM completes its final auction decision. For years, that storage, known as video caching, has been handled at no cost to publishers, first by AppNexus, then Xandr, and more recently by Microsoft Advertising.
As of April 30, Microsoft will stop providing that free caching service. From that point forward, publishers must explicitly configure a caching solution for Prebid video or risk video ads failing to render.
Microsoft has delayed this deadline once already, but the change is now firm.
Why This Matters for Revenue
If no cache is available, Prebid video bids can still win auctions, but the video file may never load. When that happens, publishers see VAST errors: the auction “wins,” reporting may suggest an impression occurred, but no video actually plays.
That means:
- Lost video revenue
- Inaccurate reporting
- Poor user experience
And this isn’t an edge case. Industry estimates suggest:
- More than 60% of Prebid-to-GAM video impressions currently rely on Microsoft’s cache
- Roughly 80% of U.S. publishers use GAM
Which means this change touches a meaningful portion of the open web’s video supply.
Why This Has Flown Under the Radar
Many publishers set up their Prebid video configurations years ago and haven’t needed to revisit them. As long as ads rendered, the system felt stable.
But this change removes an invisible dependency — one that most publishers didn’t know they were relying on. Waiting until errors appear in reporting or revenue dashboards is likely too late.
The Paths Forward (And Their Tradeoffs)
Publishers effectively have three options:
- Use a paid third-party cache
Several SSPs and video platforms now offer Prebid video caching as a paid service. This can preserve existing demand paths, but it requires:
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- Updating Prebid and GAM configurations
- Pointing creatives to a new cache
- Coordinating across vendors
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- Implement Prebid Local Cache
Prebid has introduced a local caching method that avoids external storage. While technically efficient, it currently does not work with Google IMA, which can significantly reduce AdX demand for many publishers. This may improve over time, but today it carries real tradeoffs.
- Do nothing (not recommended)
Without a cache in place, video demand may continue to win auctions and quietly fail to serve.
The Bigger Signal for Publishers
This situation isn’t just about Microsoft. It highlights a broader reality publishers are navigating in 2026:
- Programmatic infrastructure is becoming more fragmented
- “Free” ecosystem services are disappearing
- Small technical dependencies can carry outsized revenue risk
Video monetization now depends more than ever on clear ownership, explicit configuration, and active oversight.
How Adapex Helps
At Adapex, we’re already working with publishers to:
- Audit video delivery paths
- Identify hidden dependencies like caching
- Coordinate with SSPs and ad servers to ensure continuity
- Make changes deliberately — without rushing into revenue-negative decisions
We know the importance of protecting performance by understanding how demand actually reaches your site.
What Publishers Should Do Now
If you run Prebid video with GAM, April 30 should be on your calendar.
Next steps:
- Confirm whether your setup relies on Microsoft caching
- Identify which caching option aligns with your demand mix
- Plan changes early — before errors surface in production
These are solvable problems. But they aren’t automatic.
Final Thought
Programmatic video remains a strong revenue driver for publishers, but it’s no longer “set it and forget it.” Changes like this reinforce the value of staying close to your monetization infrastructure and working with partners who help you anticipate shifts early, not react once revenue is already impacted.
If you’re unsure how this change affects your setup, getting clarity now can make the difference between continuity and disruption.
