By default, vShare will not reconvert a .flv file or a .mp4 (it doesn't reconvert .flv files because it's already in the proper format. The original reason why it doesn't reconvert .mp4 files is because the flash standard allows for playback of those files. However, this, in my opinion, is a mistake because the only version of MP4 that is compatible with flash is H.264 and not the entire MPEG-4 suite of encodings). You would have to modify vShare to have it reconvert all files if you want the hardcoded mod to work on those files.