It is most likely that the various files contain CODEC's, that are either not installed on your computer, or PrE is not able to use them.
You list several file types, and I would urge you to first see this FAQ Entry, then get one of the file info utilities, linked in it, G-Spot, MediaInfo, or MediaInspector, then post the details on the various CODEC's: http://forums.adobe.com/thread/440037?tstart=0
Also, that WMP cannot play the video indicates the likelihood of a CODEC issue.
Try either of the great, free media players, VLC Player, or MediaPlayer Classic HC. Both contain many useful CODEC's, but they do NOT install them into the OS.
Good luck, and with the CODEC info, someone can give your recommendations.
Thanks Bill. I "Restored" my PC to a week ago and the problem is solved:). My guess is one of the 3 programs/updates I installed the last week week was the culprit. Adobe Air or Flash Player, Firefox 19, or Avast Anti Virus. Somehow a codec was affected/corrupted.
So glad that things are working better for you now.
Thanks for reporting.