Two examples: It's similar to the modal dialog / light box phenomenon. In that...
- The background darkens or blurs (but in a more localized fashion than a typical lightbox)
- The opening of the video/modal is triggered by clicking a link
- You can close the video, which, a) stops play, b) hides the video, c) brings back the content that the video replaced
- The video gets positioned within a specific element on the page (instead of in relation to the some page wrapper or viewport)
- The video often replaces/hides content instead of just sitting on top of it