Don't you just hate it when you open a movie clip on your Mac and it opens in QuickTime? Although QuickTime X is an improvement in terms of speed and interface on previous versions, it's still quite slow and fussy about formats. Instead, I use VLC Player to open video files on my Mac because it's fast, opens almost anything and is very light on resources.

It's annoying though to have to Ctrl-click or right-click and select Open With every time you want to open a video file with it. It's far better to set VLC Player as your default player for all video files. All you need to do is hold down the Ctrl and Alt key when you left click on a video file. Alternatively, right click and hold down just the Alt key instead. Select Always Open With and then select VLC Player and you're done!