Video Capping is a method of taking video frame captures from television video.
There are different ways to cap,
One method is using a TV tuner card with your computer.
Tuners come in a internal PCI computer card or external USB tuner.
They allow you to watch, capture, and record from Over The Air broadcast TV , Cable TV, VCR, DVR or a Sat. Dish.
Some cards also support HDTV reception from Cable TV and Over The Air channels.
Links to Tuner hardware products:
http://ati.com/
http://www.hauppauge.com/
http://www.aver.com/products/tvtuner.shtml
http://www.fusionhdtv.co.kr/Eng/products/
If you can't install a tuner card on your computer,
another method is to record shows with a DVD recorder unit and then play that DVD from your computer's DVD Drive and cap it with your computers DVD play back software.
If you need more help on what to buy or have install and setup questions visit the "Tech Support/Reviews" section of the WWofW forum.