Unable to download movies (mp4) after upgrade to leopard

After upgrading to Snow Leopard 10.6.8 I have not been able to download any more movies.

I save link to desktop and the format line says: Quicktime Player D. But after downloading here is the message upon trying to open movie:

"The document “FIRST AID KIT BASICS MOVIE 18-52-52” could not be opened. QuickTime Player cannot open files in the “data” format."

I did update Quicktime - had a bunch of other issues with other programs after upgrading operating system but those are all taken care of now. This remains my only problem.

Found a solution suggesting to update Flip4mac which I did. Now I get “the document.....could not be opened. The movie is not in a format that QuickTime Player understands."

Thanks.

Nancy