Ok, first of all, when you go to the first frame of the music and go to "properties", it will have an "sync" dropdown menu. Yours is set to "stream" which forces each frame to stay perfectly in sync with the music, that way, if the frames aren't playing fast enough, it doesn't get out of sync after a while. If you want it to play smoothly through to the next scene, you want to set it to "event". Now, doing this may sacrifice some synchronization, but it's the only way. For me, I like to make sure that no matter what computer it is being veiwed on, it will stay in sync with the audio, so I just copy/paste the scenes together in the final cut.