Helge's work would add support for compressed images and audio to be passed through the X protocol. By doing so, playback synchronization would be handled by the X Server and would allow for some network transparent media players.
If this code ends up entering the mainline X Server, it doesn't look like it will be committed anytime soon since there is still quite a bit of work left. The current work is very low-level with a higher-level interface still being needed, there is currently no hardware-accelerated decoding, there are severe latency problems with the X Server until that becomes multi-threaded, and an audio/image de-compressor would need to enter the X Server.
Below is Helge's X multimedia talk.