Quicktime Player (X or version 7) doesn't support playlists to my knowledge. You could add the files to a playlist in iTunes, or download [VLC](http://www.videolan.org/vlc/index.html). I'd highly recommend VLC, it's free, it can tackle pretty much any format you can throw at it (including .mov), and you can just drag and drop files to a playlist to queue them up very simply.