Bugfix for showing Bulgarian subtitles

Unfortunately Bulgarian subtitles are still stuck in windows-1251 land and never moved to using utf-8. Right now all subtitles are referenced in the player as utf-8. This is a really simple fix to use the windows-1251 charset when the subtitle language is Bulgarian. Right now I don't think it's possible to inspect the actual subtitles and dynamically select the charset, since we're not preloading the subtitles and just referencing them as an url. Correct me if I'm wrong.