I’ve got this file that has the extension.avi
I tried using windows media player and quick time but both didn’t work…so how?
You probably don’t have the right codec installed. Right-click the file, choose Properties and then click on the Details tab. Write down the Audio Format and Video Format information and post it here and we can probably help.
WAG: divx.com
It may be that you do not have the correct codec to open the file. Perhaps it is in DivX format(quite likely if you DLed it from a certain file-sharing service that I won’t mention here), in which case you need to go to www.divx.com and install their stuff.
Failing that, it might just have the wrong extension… try changing it to mpg and see if that works (windows is amazingly stupid about these things)
yow! A triple sim-post. My very first 
At least everyone seems to agree with my diagnosis