It seems some Google videos have a '-' in the URL to work. I feel this is an inconsistency that Google Video developers have put in so maybe its something beyond your control.
What I suggest is having the option to allow the Editor to put in the whole Google URL, and then you can strip the right DocID from the URL and use that in your code as the DocID which will work. This will work for all cases then.
I'm OK for MySpace (I don't know it, but why not?)
But I don't think media player is a good idea. MP is not installed on all platforms, some format use codec not available on all platforms. My friends on mac don't read the .WMV (Windows Media Video) files. But GoogleVideo accept WMV files, upload your files to google and use Google Video extension, that's better. GoogleVideo flash program send to user the best format depending on his system, screen size, probably download bandwith...