I having as same as trouble like you. I was using it for almost a year but suddenly they won't work at all. i thought that Yahoo do not want to update anymore since all kind of Browser had been update so fast, and now I believe that Yahoo Media Player had been obsolete.
I don't think "deprecated" is the correct term, since the file was removed from the official url.
Any comment on suggestions for replacement?
Any hope of open sourcing it?
It is still available under the "player-beta.js" file name on the same site. Can we rely on this for at least a few months until we find a replacement, or code our own replacement? I imagine a YUI based replacement would be attractive for many, and it would remain supported in the third party Gallery community.