Text associations for HTML5 video/audio

Hello list,
Here is an alternative proposal for integrating text associations into 
HTML5.  Although I personally feel that we should consider more general 
models of temporal composition to solve this sort of problem, the 
solution presented here limits the damage of further bloating <video> 
and <audio> -- and it has functionality that could also be useful for 
differentiation screen and connection speed constraints.

I welcome you comments.

Dick Bulterman