Instructions:
Press play on the audio file first, then when instructed to in the track, wait for "3", "2", "1", "PLAY." When it says PLAY, you can press play on the Youtube video above and watch them simeltaniously to achieve the effect of a comentary track.
If it doesn't sync at first, I suggest letting it buffer a little then pressing play without it being the thumbnail image and actually the embedded player.
Make sure to have the Youtube volume set somewhere around here: