Download these two programs:EVEREST Home Editionhttp://www.softpedia.com/get/System/System...e-Edition.shtml
EVEREST Home Edition is a free system diagnostics, system information and benchmarking solution for home PC users, based on the award-winning EVEREST Technology. If you don't know what type of video card you have, or anyhting else about your computer, then you'll need this.Eusing Registry Cleanerhttp://www.eusing.com/free_registry_cleane...try_cleaner.htm
Eusing registry cleaner is a fast and FREE, and most importantly, very good at cleaning out bad registry entries. Even if you use other registry cleaners, you should definitely add this one to your list.
After downloading the Everest, start it and get your video card info. After that, use the registry cleaner and clean your registry, reboot, and try your videos again, then post back.
What program(s) are you using to watch your videos, besides VideoLan?