Hi,
I believe it would be great providing the ability to add interactivity to a video. Perhaps, this could be implemented by overlaying existing Xerte pages on top of the video (using z index). Users would need to select the video first (from YouTube, Vimeo, etc.), and then specify the time and the Xerte page that should be displayed. These embedded Xerte pages could have the option of being hidden from the regular navigation of the project. This would allow instructors to display additional information about a specific segment in the video or add several type of knowledge check questions... just a thought.