I'm not aware of any particularly good solutions for this, particularly any that could create data viewable in multiple players and not just the source app. So I too am very interested in any more informative responses. I do believe this sort of thing was going to be a part of the MPEG4 spec at one point, or perhaps the upcoming MPEG5. Hopefully that comes to pass for MPEG5 at least because then it would be a standard and many players would have support for it.
- Oshyan