can you share the link to exactly where you downloaded them from. So I can see the technical information about the files.
What version of AE? It should be up to date. How about Quicktime. There were QT issues with Windows machines and previous versions of AE. What about your OS? Without system details and some more information any answer you get will be a blind guess. We are throwing darts blindfolded.
With the footage selected in the Project Panel you should see some specifics like this:
Your project panel shows this:
This tells me that the file is corrupt or you don't have a current version of AE and the appropriate Quick Time updates, or it is in a format that is not supported on your machine even with the updates.
Try opening the movie in the QuickTime player and find out what size, frame rate and format the movie is supposed to be.
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