you can't burn AAC video because it's an audio codec. BUT if you are looking to just burn the sound from your DVDs to AAC this can be done rather easily. infact there is an AppleScript that will do it for you. can't remember where i saw it. search around and you'll find it. if not, you could always use WireTap or Audio Hijack. be prepared to take up alot of disk space with the raw audio though.