VLC, Sorenson & H.264/AVC Video

[hgratp]

I have been experiencing difficulties trying to watch .flv files in VLC decoded with H.264/AVC Video streamed from youtube (slow connection). They play fine in totem but I receive an error in VLC 0.9.4:

No suitable decoder module:
VLC does not support the audio or video format "undf". Unfortunately there is no way for you to fix this.
No suitable decoder module:
VLC does not support the audio or video format "undf". Unfortunately there is no way for you to fix this.

I downloaded the ubuntu-restricted-extra package just in case and was under the impression VLC would not present problems playing this files.

Also, I am using the DownloadHelper 4.1 addon for Firefox 3 and it some times would download the file encoded with Sorenso and in other instances
H.264/AVC codec. Is there anyway to set Sorenso as default since I have no problems watching the .flv in VLC encoded with Sorenso or does that depend on how the video was uploaded to youtube?

Thanks in advance for any help. Running Ubuntu 8.10 - Gnome 2.24.1

[akssoon]

Bump, for I have the same problem!

Neither MPlayer nor VLC are able to open the file. Both "can't find the codec".

Totem is able to play the movie file but no seeking is possible, which makes it pretty useless :-(