I'd personally prefer having talks downloadable in a standard format (say, mpeg) rather than only via justin.tv, but they're still much better than nothing. (Or maybe they have a download feature I haven't been able to find?)
ls -ltr /var/folders/jH/jH90qqJaGnOB1gJOwGbGKE+++TI/TemporaryItems/
on my Mac
BUT, happy they're stream-able period! I will sadly not be in the area, but look forward to seeing it online.