AVAudioplayer continue to play sound while UIWebView is playing embedded video

Question

I have this issue with mu AVAudioplayer continue to play sound when I play an embedded video in uiwebview inside my app.

If I play the video from safari, it works fine, the audio from my app will fade out then stop to begin play the video from Safari.

Any recommendation is appreciated :)

Xcode 4.5, iOS 6

Thanks