Audio out of sync with video in HTML5

Hi, I have a music file that plays for 5 seconds with a dancing character. The character is in sync and ends when the music ends.

When exported, the dancing character is very slow and behind the music in time. The music ends and the visual still needs another maybe 2 secondes to finish. How do I get it to sync with the audio??

Side question: Those that are using AS3, are you publishing to swf?? If so how are you using swfs if browsers don't run flash anymore?