If you want a simple - quick and dirty - way to edit a video, there's nothing to surpass Quicktime Pro from Apple. When you just want to chop a bit off a video file or splice a few videos together (assuming they are encoded the same). And I am talking about Windows and specifically with version 7 of QT Pro. It is incredibly easy to use, it's fast and lossless. (That means it doesn't actually convert or re-encode video, so it doesn't lose anything.)
As a video player, it is unnecessary. As Apple says:
However Apple, in its wisdom, decided to retire this gem. It still works now and can be installed. I still have a license and can use it, but there must be some suitable alternatives for when Apple finally closes it down? Or when Windows no longer plays ball.