Once in a while, a flv (flash) video I have download from the internet from sites like YouTube (using CosmoPod) will not play video when opened in QuickTime. The space for the video is there in the QuickTime window, but it is all black. Audio plays fine. This only happens for some flv files and I can open them all just fine with VLC and Adobe Media Player. Any idea why this is and/or how I can fix it?