I just plugged my GoPro into my computer and downloaded all of my footage. This is my first time transferring my videos onto my computer. When I try to play the videos (that are in an .mp4 file), I hear the correct audio but the video just shows a black screen. I know that the file contains the right video because I have been able to successfully view the videos on other computers. This leas my to believe that the problem has something to do with my computer. Any ideas or fixes would be greatly appreciated.