if you're unhappy with imagegrabber ii because it misses any batch functionality, may this free tool is the one to fall in love with: Scenegrabber.
http://anonym.to/http://www.scenegrabber.net/
download the latest version and the FFmpeg addon (if you don't have it). install and place the FFmpeg addon into the installation folder. When you start the program, enable FFmpeg in AddOns menu.
batch processing works pretty easy, but before you use it on all your movies play a bit with the settings you can make to gain the desired layout. if you're familiar with settings and results of imagegrabber ii, you will be happy with that what scenegrabber offers. it's very similar and finally the processing speed is much better.