In-Stream Video Ads
From IAB Wiki
Played before, during or after the streaming video content that the consumer has requested. These ads cannot typically be stopped from being played (particularly with pre-roll). This format is frequently used to monetize the video content that the publisher is delivering. In-Stream ads can be played inside short or long form video and rely on video content for their delivery. There are four different types of video content where in-stream may play, UGC (User Generated Content/Video), Syndicated, Sourced and Journalistic.