Check this issue:
http://code.google.com/p/get-flash-v.../detail?id=249
and visit this page:
http://r.hulu.com/videos?content_id=50119747
You can see:
Code:
<pid>NO_MORE_RELEASES_PLEASE_50119747</pid>
Hulu is becoming smarter and asking for no more releases of software to record its videos.