So I downloaded a video off Youtube with this iLivid program I installed. So I play with VLC Media Player and then this error pops up saying "VLC does not support the audio or video format "undf". Unfortunately there is no way for you to fix this." But then the video plays anyway, and it says it's a flv file. So I'm confused which it really is, and should I be worried even though VLC just played it. I intend to have the video attached via e-mail.