Currently Being ModeratedApr 25, 2013 11:33 PM (in response to A Fisher)
You are looking at Aperture's cache in $TMPDIR.
Usually it is no problem to delete the contents of this cache, if Aperture is not running. But it is suspicious, that the videos have not been removed automatically, after Aperture quit.
Check the permissions on the $TMPDIR folder, if you are still the owner. If you are not for some reason, reset the ownership to yourself.
Log off and on to terminate any running processes. Open the Terminal and enter:
sudo chown -R $UID $TMPDIR..
You will need to enter your admin password.
Then test, if Aperture clean the cache on its own, after you relaunch Aperture.
Otherwise remove the videos yourself after quitting Aperture.
P.S: Is there any related problem that made you browse the system cache files?