The documentation on the Video node was recently updated (
https://sdkdocs.roku.com/display/sdkdoc/Video). Hopefully, this more clear:
Video.content:
The ContentNode node with the Content Meta-Data for the video, or a video playlist (a sequence of videos) to be played.
If a video playlist is to be played, the children of this ContentNode node comprise the playlist, and each ContentNode child must have all attributes required to play that video. For example, if the videos "A" and "B" are to be played, three ContentNode nodes must be created: the parent ContentNode (which is largely ignored), one ContentNode child for "A," and one ContentNode child for "B." The parent node is set into this content field, and when video playback is started, all of its children will be played in sequence. Any changes made to the playlist after playback has started are ignored. See the contentIsPlaylist and contentIndex fields, for more information on playlists.