vshare do not use any codec, it use ffmpeg or mencoder to do the conversion. So if ffmpeg or mencoder is properly installed, video conversion will work.

By default, it will be mencoder (as it support more format, if properly installed). You can switch to ffmpeg if you need, more details available at

http://forums.buyscripts.in/viewtopic.php?t=352

You can see what command used to convert video on your site by checking templates_c/debug.txt file.