You can try messing with Quicktime's setings under edit/preferences. Also try closing all processes that might be using/clogging your internet connection. It's also possible that Piens doesn't have a big enough bandwith or fast enough connection.
I'm no expert in computers, but noticed that after the first song is over and all those colored lights stop turning on and off the video and audio stabilized and everything went smoothly, so I don' know if that has anything to do with the problem. Anyone noticed that?
Anyway I hope that helps.
Good luck and keep trying cause it's worth the effort.