Ok, any of the videos work when I play them in VLC. Thank you for that.
HOWEVERThey DO NOT WORK IN ANY OTHER MEDIA PLAYER (such as Media Player Classic or Windows Media Player). There's always an error message!
And when I open any files in any WINDOWS EXPLORER FILE, the computer always goes haywire, and there's always a message saying that "Windows Explorer has experienced an error and needs to shut down" etc, etc.
HOWEVER,
When I open any video file (ON VLC) ON THE DESKTOP, there is no problem!
*censored* is happened to my computer???