See this clip, around the 1.01 mark. http://www.youtube.com/user/movieclips?ob=0 See how there are links to other videos inside the video. Is this done via the usual "in embed" annotations, that anyone can do, or is it done through some special service that this very popular YT channel has access to? Is it done through the API or is it done manually? I would like to know how one could go about to: 1. Specify other videos to watch in the same way 2. Have the videos chosen from the same category in my channel. I know this is a pretty complicated question. But I am certain there is some geek out there that knows how this works.