Implementing Outstream Video Ads with Prebid.js: A Practical Guide for Publishers
Outstream video ads let publishers monetize web pages with video inventory—even if those pages have no existing video content. Unlike instream video ads, which require an embedded video player, outstream opens up new monetization opportunities for text-heavy or mixed-content pages.
For technical and ad ops teams, adding outstream video to your Prebid.js setup is straightforward. This guide demystifies the process, clarifies the role of renderers, and walks through integration paths that minimize disruption to your existing stack. If you already run display with Prebid.js, you’re closer than you think to unlocking valuable video demand.
Understanding Outstream Video Ads in Prebid.js
Outstream video ads are delivered independently of a site’s video content. Instead of requiring a video player, they display in non-video placements—like within or between paragraphs—on any web page.
Why Outstream?
Instream video is limited to video content, but outstream allows publishers to activate video demand on any page. This increases available inventory, fills more impressions, and often accesses higher CPMs due to video ad budgets.
Technical Differentiation
From a technical perspective, setting up outstream is much like configuring a standard Prebid display ad unit, with only minor adjustments needed for the video media type. There’s no requirement to overhaul your stack or workflow.
Setting Up Outstream Video Ad Units
To enable outstream, publishers define ad units with the video media type and specify an ‘outstream’ context in the Prebid.js configuration. This signals to demand partners that the ad slot is not tied to an existing video player.
Example Prebid.js Ad Unit Configuration
A typical setup looks like this:
– code: ‘video1’ (HTML element ID for the ad)
– mediaTypes:
– video:
– context: ‘outstream’
– playerSize: e.g., [640, 480]
– mimes: [‘video/mp4’]
– other standard video params (protocols, skippability, etc.)
– bids: array of demand partner configurations supporting video
This minimal change lets you leverage video demand with a similar process as display.
Choosing Demand Partners
At least one demand adapter supporting video is required. Assess which existing partners support outstream and test their demand in standard layouts.
Renderers: How Outstream Video Gets Displayed
Outstream ads require a player—called a renderer—to display video outside of traditional video content areas. Publishers control which renderer is used, adding flexibility and reliability in delivering the creative.
Renderer Priority in Prebid.js
Prebid.js determines which renderer to use by priority:
1. Renderer defined specifically for the video media type (preferred for precise control).
2. Renderer set at the ad unit level (applies to all media types if not overridden).
3. Renderer returned by the winning demand partner (last resort; not all partners supply one).
Best practice: Explicitly assign a renderer to your outstream ad unit to ensure compatibility across all demand sources.
Renderer Configuration Tips
A renderer is an object with a render function and (optionally) a URL to a JavaScript file. Some demand partners let you pass configuration options, like custom ad text or player controls. This allows publishers to control user experience and branding for video ads rendered outside the standard player.
Serving Outstream Video: With or Without a Primary Ad Server
Prebid offers two main ways to serve outstream video:
1. Through your existing ad server (e.g., Google Ad Manager)
2. Directly from Prebid.js, bypassing the ad server
Option 1: Using an Ad Server Like GAM
Place the Prebid-outstream ad unit directly in the body of your page, as you would a display unit. The ad server handles targeting and delivery, ensuring outstream plays well with your existing yield strategies.
Option 2: Directly via Prebid.js
For sites not using a primary ad server—or for special placements—you can request bids and render the video on-page with Prebid.js alone. This approach provides flexibility but requires more direct handling of bid selection and rendering in your page code.
What this means for publishers
Outstream video enables publishers to expand video ad inventory without producing native video content or altering site layout. It leverages existing Prebid.js expertise and infrastructure, reduces implementation barriers, and provides operational control over the look and behavior of video ads. Demand sources may increase, and with careful renderer selection, publishers can avoid creative incompatibilities that sometimes cause video ads to fail to render.
Practical takeaway
If you already use Prebid.js for display, enabling outstream video is straightforward—define new ad units with the video media type set to ‘outstream’, and ensure you have at least one demand adapter that supports video.
Assign a renderer explicitly to your ad units to guarantee cross-partner compatibility and a consistent user experience. Consider experimenting with both ad server and direct Prebid.js approaches to determine what fits best with your revenue operations and technical constraints.
Regularly monitor your outstream placements for viewability, engagement, and revenue impacts, and be ready to fine-tune your renderer setup and demand partners for optimal results.
