[WIP] V4 convert mediaplayer coffee

## DO NOT MERGE

Initial conversion back from CS for the multimedia player.
- There are JSHint errors due to undeclared variables
- See `FIXME` notes
- `TODO`s can be left for a later date
- Verify return values because CS is odd

/cc @patheard, @masterbee, @LaurentGoderre, @pjackson28 your turn for revenge :smile: