No video recording with alpha version of Flashplayer for linux x86_64

Video recording doesn't work under Ubuntu Hardy 8.04 64bits + Mozilla Firefox 3.0.4 + Flashplayer alpha release from :

http://download.macromedia.com/pub/la...

"start recording" after allowing access to camera has not effect.

Only enabled choice is "cancel".

Internal webcam works with other applications, like cheese for example.

Did you hear about such a problem ?

Where can be the source : flasplayer alpha or seesmic code ?