There were a number of people who were unable to watch the complete Creating Themes for BlogEngine.NET webcast. (The screen turned red at some point in the webcast. It seems to be a memory consumption issue.)
I went ahead and made a Windows Media version available for download. You can download it here. It is huge, but it works fine (at least for me).
I also updated the flash movie, but it is still a large file so you could still have trouble.