I’ve had some problems with Flash videos having choppy audio in Ubuntu, lately. The internet is rife with people having similar problems, arriving from different root causes but posing similar symptoms. I’ve had this problem several times, and each time, I poke around the internet again for a solution, because I can’t remember what worked for me before. So now I’m finally writing it down. For some reason, killing the pulseaudio server (and letting it start up again) solves the issue.