It looks, in fact, like the .wmv or .mp4 file is fucked, but it isn't, the same file plays fine on other computers.
I have an older, less capable computer, and the symptoms you describe are things I see when there are not enough CPU cycles available to render things properly.
Lots of things can cause that, including malware chewing up cycles and not having enough swap space available because your hard drive is full.
Take a look at your task manager and see if you are near 100% utilization. Installing a codec pack is not going to help.
Also the VLC video player plays just about everything without having to install codecs.
Edited by NoNukes, : No reason given.
Edited by NoNukes, : No reason given.
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass