Update: More recent versions of QuickTime Player have the ability to copy frames of the video by using 'Command + C'. In recent versions, to grab a frame, do the following:
- In QuickTime Player: Pause on the frame you want to capture (use arrow keys to go forward/backward by 1 frame).
- Press 'Command-C' (or select Edit > 'Copy').
- In Preview: Press 'Command-N' (or select File > 'New from Clipboard')
- Save the new file where you'd like.
There are many things to like about QuickTime X, and many improvements were included over QuickTime Pro 7... but there were also a ton of features removed (like being able to set advanced export options, save a movie as images, and do some other more advanced edits/exports.
However, I'm glad I finally figured out how I can grab one frame from a movie in QuickTime Player X. The problem I was having is this: If you pause the video and use the left/right arrow keys to move the playhead exactly to the frame you want, the player controls are still showing over the video (in addition to the video title bar/window chrome.