Hi, I wonder if anyone can help? I have Quicktime, Peri, VLC Player, DivX and none of them will play mp4's, AVi's or anything video related. My flash player is up to date and plays youtube videos no problem. I am using Yosemite if that's any help? Files always start to open, says converting and then comes up it can't open. I'm a bit of a novice so any help would be much appreciated. It's such a pain!!