It doesn't look like they are up just yet.... got to the AHA page, under Events, drop down to National Homebrewers Conference, and there are seminar and audio presentations, but it looks like the 2012 ones aren't up.... That being said, I'm not sure if they will keep the audio ones from last year up once they post the new ones, they only have 2011, but that may be the first year they posted them?? They have seminars going back a few years...
http://www.homebrewersassociation.org/pages/events/conference/audio-presentationsYou can access Chad Y.'s Brett Brewing talk though...