The videos from pre-GDC 2009 on their website seem to be mostly (all?) flash-based. They say "Get the Flash Player to view this session.". As flash is discontinued, I tried a flash emulator browser extension, called ruffle. It opens the video player, but the video doesn't play.  

The videos are not archived somewhere on youtube, other video streaming website, archive.org, or torrent. I'll be happy to be proven wrong though.

Anyone knows a solution?