Video segment presentation tracking

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for tracking presentation of content. In one aspect, a method includes segmenting a video into two or more segments. Each segment of the video can be a variably selected disjoint subset of the video. A client-side video player determines that playback of the video has reached the end of one of the segments. A presentation type for the video is determined, where the presentation type being one of an advertisement presentation or a non-advertisement presentation. The playback data is provided to a server-side data processing apparatus that stores the playback data in a data store. The playback data indicate the presentation type for the video and that playback of the video reached the end of the one of the segments.