I thought that I'd pass this tip on to the group here. I have found YouTube will not accept the .ogg/Vorbis video files generated with gtk-recordMyDesktop.
Once you record your vid it should land in your /Home folder, you can convert it with the following -
Here's the how-to. Firstly you'll need mencoder installed. Get it through Synaptic.
Then in shell run either of these two commands:
mencoder -o output_file.avi -ovc lavc -lavcopts vbitrate=5000:vhq -ffourcc DX50 -oac pcm -srate 48000 -ofps 25 your_movie.mov
mencoder -o output_file.avi -ovc lavc -lavcopts vbitrate=5000:vhq -ffourcc DX50 -oac pcm -srate 48000 -ofps 29.97 your_movie.mov
I assume your Vid is in your Home file. Then where it says "your_movie.mov", change it to /home/whatever/your movie name. Click, and your vid gets converted to an .avi file. It might take a minute or two. The .avi should land in your Home file.
Happy YouTube posting!