Maybe this is another "feature" I don't appreciate?
On running a QuickTime movie today I discovered
(a) I can't bring it to the front when other apps are running
(b) I can't reposition it on the screen
(c) I can't switch to other applications.
Just thought I'd let you know.
Please don't offer suggestions along the line of "you're doing something wrong".
Did you install a 3rd party preference pane for Quicktime X on Snow Leopard?
If you disabled the hidden option "Rounded Corners" it will produce effects like this on Lion.
Either switch it back in the pref pane or (if you do not have it anymore), the following defaults command will do it:
defaults write com.apple.QuickTimePlayerX MGCinematicWindowDebugForceNoRoundedCorners 0