I finally found the way (again).
I needed such a way so that I could upload youtube videos of my screencasts. For some reason Youtube did not like theora vids, even in .avi format (something about my 1 min, 1Mb vid exceeding limits).
All I had to do after all to convert it into the more popular format after capturing it with Istanbul is:
mencoder input_file.ogg -ovc lavc -nosound -o output_file.avi
Instructions found here
This post is in part here to jog my memory in case I forget once more in the future.