If you want to pull frames quickly and easily from your video clips, then you should take a close look at MovieDek from Limit Point. MovieDek is a video utility that'll scan a video file and export a range of frames as stills in just a few minutes.
MovieDek is a bare-bones app that launches with a small dialog box in the center of the screen. The app instructs you to drop a movie file on the application or the window to start the extraction process. There's also a preferences button and a quit button if you want to shut down the app. Inside the preferences, you can set the scale of the exported images as well as the image file format and image quality. You can also select the range of frames that you want to export.
