I'm the AV wrangler for LCA 2013, and we know that there are problems with some talks. Some were truncated because of render failures, some we just didn't piece together completely out of the raw files, and some just had other problems. I've been updating the header information on http://mirror.linux.org.au/linux.conf.au/2013/ogv/ (and mp4/) as things progress. Please have some patience with this process as I'm having to do most of the work by hand remotely now that the equipment's been moved to a building within ANU and I haven't :-)
I'm glad to see people enjoying the videos despite the few flaws.