Implementing Prebid Instream Video with VideoJS: A Practical Guide for Publishers

Video advertising has quickly become a top monetization strategy for publishers, but getting instream video header bidding right is not always straightforward. Prebid.js offers publishers a path to increase video ad yield and transparency in a landscape often dominated by walled gardens.

This article guides publishers and ad ops managers through the process of setting up instream (pre-roll) video ads using Prebid.js and VideoJS. We’ll focus on practical implementation, highlight common pitfalls, and clarify what you need to know to run a high-performing and compliant video ad stack.

Understanding Instream Video with Prebid.js

Instream video refers to ads shown within video content, typically as pre-rolls. Unlike display ads, instream requires close integration with both the video player and ad server, plus strict adherence to VAST/VPAID standards. Prebid.js enables header bidding in video by collecting bids before the video plays, increasing competition and CPMs.

Why Instream Is Different

Display and outstream header bidding deal with static ad slots, but instream requires the player to dynamically load, initialize, and play ad creatives based on live auction results. This means video header bidding flows must closely sync with the underlying video player—such as VideoJS—and any required plugins for industry compliance.

How Prebid Integrates with VideoJS: Step-by-Step Flow

Prebid.js does not play video ads itself; instead, it orchestrates the auction and returns a URL (usually a cached VAST XML) that the video player will use to render the ad. For publishers using VideoJS, this means integrating Prebid auction logic into the page and passing the resulting VAST tag to the player via the videojs-vast-vpaid plugin.

Technical Flow

– Using a “kitchen sink” build of Prebid.js with every adapter bloats page weight. For production, always custom-build Prebid to just the adapters you use.
– Default placement IDs in code examples are only for testing. Always use your own IDs to ensure revenue tracks to your network.
– Failing to match player size or MIME types between Prebid config and video assets may result in unfilled ad slots.
– Omitting required VAST/VPAID plugins or using outdated versions can cause ads—especially on iOS—to fail.

Optimizing for Revenue and Player Compatibility

Technical set-up is only valuable if auctions compete and creatives show up reliably. To maximize yield and compliance, configuration tuning and frequent QA are essential.

Key Publisher Considerations

– Always enable VAST caching. This ensures the winning ad is accessible to your player, avoiding empty impressions or ad failures.
– Ensure the videojs-vast-vpaid plugin is up to date and matches your VideoJS version, especially for mobile support.
– Use pbjs debug mode during QA to log auction and playback events; this can pinpoint creative or latency issues.
– Coordinate ad server line items (e.g., in GAM) to expect header-bid video demand and prioritize accordingly.

What this means for publishers

Prebid-powered instream video lets publishers regain control of auction dynamics in their video ad stack, driving up competition and margin. Operationally, this means more configuration overhead—but also greater ability to troubleshoot ad delivery, enforce compliance, and test new revenue partners without waiting on vendor roadmaps.

Practical takeaway

For publishers, the path to instream video header bidding starts with a technically robust, minimal setup: custom Prebid.js build, strict use of production placement IDs, current player plugins, and VAST caching. Get these fundamentals in place before expanding demand partners or tweaking revenue optimization strategies.

Regular testing is crucial: use video-specific test creatives, log every auction outcome, and keep QA scripts in sync as player or Prebid versions change. Lastly, ensure your ad server line items are built to co-exist with header-bid video. With these practices, publishers can unlock the full potential of instream video without risking wasted inventory or player failures.