The short answer
Instream video ads play before, during or after video content that the viewer came to watch: the pre-roll, mid-roll and post-roll inside a video player. Outstream video ads play without that surrounding video content, for example in a unit between the paragraphs of an article, in a feed, or in a banner or anchor slot. Google Ad Manager calls them non-in-stream ads and describes them as ads that appear outside of a video player and have no surrounding video content. Since 2023 the industry vocabulary has had four categories rather than two. The IAB Tech Lab's placement list separates instream from accompanying content, a player on a page whose main purpose is something else, and splits outstream into interstitial and standalone. The labels matter because buyers can target each type separately and because publishers have to declare them correctly in their ad requests.
The four placement types in the IAB Tech Lab list
The IAB Tech Lab's AdCOM 1.0, the object model used by OpenRTB 2.6, defines a video placement field called plcmt with four values. Value 1, Instream, covers pre-roll, mid-roll and post-roll ads around streaming video content, where the video starts with sound on by default or the user clearly intends to watch it, the video is the focus of the visit and it is the only player in view capable of audio. Value 2, Accompanying Content, covers the same pre-roll, mid-roll and post-roll ads around streaming video, but in a player that loads between blocks of text or graphics and starts playing only when it enters the viewport; it may become a floating or sticky player as the user scrolls. Value 3, Interstitial, covers video ads played without video content that, while playing, are the primary focus of the page, fill most of the viewport and cannot be scrolled out of view, for example in-app video or slideshows. Value 4, No Content or Standalone, covers video ads played without streaming video content in slideshows, native feeds, in-content placements or sticky and floating units. The older placement list was marked deprecated as of the 2.6-202303 release. In everyday terms, values 1 and 2 are what used to be loosely called instream, and values 3 and 4 are what most people mean by outstream.
What makes a placement truly instream
The test is the viewer's intent, not the player technology. Google Ad Manager's video inventory policy defines in-stream as an ad within a stream of content that is the focus of the user's visit or explicitly requested by the user, such as a pre-roll on a video the user clicked to play. Accompanying content is an ad in a stream of video that is neither the focus nor requested, and those placements must be muted by default; Google's example is an auto-played muted video in a small part of an editorial page. So a muted player that starts on its own at the top of an article is accompanying content, even though it runs pre-rolls in a real video player. In Ad Manager, publishers declare the placement type with the plcmt parameter and audibility with the vpmute parameter, and both in-stream and accompanying content placements must use the IMA SDK or PAL. The same policy sets autoplay limits: only one video across all placement types may autoplay with sound at a time, only one in-stream or accompanying content player may autoplay in view, and an ad must not autoplay until at least 50 percent of its unit is visible. Sticky video is allowed if a dismiss option stays available for the whole time.
How outstream ads behave
Google Ad Manager serves non-in-stream video in display formats such as banner and anchor, and they are on by default; a publisher can turn them off with the Block non-in-stream video ads control. Ad Manager does not ask for a placement declaration here: it classifies these ads as interstitial or standalone based on the inventory format, and they must run through Google Publisher Tags on the web or the Mobile Ads SDK in apps. Playback is muted and starts when 50 percent of the ad unit is visible, and the video pauses when it leaves the view. The impression counts when the first frame renders. The ad autoplays for up to 30 seconds while in view and can play longer after the user taps or unmutes; afterwards an end card shows the last frame with a Learn more button. Where a browser blocks autoplay, a poster image appears and the user has to click to play. Google recommends slots of at least 256 pixels in both dimensions, 4:3 or 16:9 for horizontal, 3:4, 4:5 or 9:16 for vertical and 1:1 for square video, and a maximum length of 15 to 30 seconds, noting that much longer videos tend to get fewer completed views. On the buying side, Display & Video 360 describes its outstream ads as non-skippable and served only in the main body of the page, not in sidebars, headers or footers, and says advertisers pay only for viewable impressions, which for video means at least 50 percent of the ad's area in view for at least 2 seconds.
Trade-offs for publishers
Instream inventory depends on video that people choose to watch, so its volume is set by the library and by how many visitors come for video. By definition it carries the clearest intent signal of the four types.Accompanying content lets an article page carry a player with pre-rolls, but it must be declared as accompanying content and play muted by default; calling it instream does not match either the IAB Tech Lab or the Google definition. Outstream needs no video content at all, so it can run on text pages and in feeds, but it plays muted, sits next to the article the visitor came to read and only counts for buyers who pay on viewability when it is actually in view. Each type also has a user experience cost. Several autoplaying players, sticky units without a close button or ads that push the text around compete with the content the visitor came for, and some of those patterns are ruled out by the policies above. Compare placements on the same measures: starts, viewability, completion by length and the effect on the page's own engagement, not revenue alone.
Where Minute-ly.com fits
Minute-ly.com generates video experiences such as Top Videos, Video Previews and vertical versions through Smart Composition, and its video products can support sponsorship, branded transitions and advertising within the generated experience. A transition between two stories can carry an approved brand creative, with its placement, duration, labeling and frequency agreed with the publisher, and a commercial partner can sponsor a Top Videos or vertical experience directly. Whether a given placement counts as instream, accompanying content or standalone follows the same definitions described here, so its format and inventory classification are agreed with the publisher and its ad partners before launch. Programmatic demand is not available everywhere: it depends on the player, the demand connections, the policies and the commercial agreement. Revenue, fill and ad delivery are tracked together with viewing behavior, so a new placement is judged on both, and more video assets do not guarantee more revenue.
Checklist
List every video placement on your site and app and assign each one a plcmt value: instream only where the video is the focus of the visit or the user asked for it. Declare muted autoplay players in articles as accompanying content and keep them muted by default. Pass placement and audibility correctly in every ad request, and keep the legacy placement field only for partners that still read it. Allow one autoplaying player with sound at a time, start ads only when half the unit is visible and give sticky players a close button that stays available. For outstream, use slots of at least 256 pixels, offer the aspect ratios your layouts support and keep creatives to 15 to 30 seconds. Decide whether outstream belongs on each template or should be blocked. Measure each type separately on starts, viewability and completion by length, and watch the effect on the page's own reading and viewing.