I like the work so far. You could use Gnash http://www.gnu.org/software/gnash/
the FOSS version of Flash. And since most users will be editing on a desktop machine, not repurposing their TV for editing, using flash is less of an issue.
You don't have a delete for a song added that isn't wanted. The reordering didn't seem to work for me. Possibly because I have a bad entry in the list. I'll get some input to you on functionality and graphics in the next few days if you want. . . I think this is a good start on a better content manager than LMCE currently has.
Would it be possible to suppress attributes that may not make sense, like some of the video ones for music content?
And adding a complete album in one pass would be nice.