Well, I had a little glitch with iMovie and my Sony Handycam movies. I very happily had everything working
nicely with sound for my MPEG2s in iMovie then perian updated itself and broke something, so that sounds for my movies stopped working. Just uninstalling and reinstalling perian did nothing to help. However, reinstalling iMovie (actually iLife ’09) fixed the problem. Clearly perian is doing something to one of the sound libraries that messes up iMovie, though what I have no idea. Anyway, I’ve stopped perian from automatically updating itself in the hopes that I won’t have this problem again. Maybe this tip will help some other hapless Mac user with MPEG2 formatted movies……