I received the message above "This movie requires QuickTime, which is not included in this version of iTunes. To play this movie, install QuickTime." I then uninstalled/reinstalled QuickTime, but I still cannot play my video files in iTunes U. Help?!?

When I tried downloading and playing a video in iTunes for iTunes University from my college course link, I received the message "This movie requires QuickTime, which is not included in this version of iTunes. To play this movie, install QuickTime." I then uninstalled/reinstalled QuickTime, but I still keep receiving the same message. What step(s) am I missing to get this corrected? Thanks for any help.