Depends what you mean by shop bought videos. Do you mean DVD's or video files you purchased over the internet?
For iPod, videos need to be either MPeg 4 or H.264 format which is an advanced version of MPeg 4. H.264 is the better format (same as blue ray disks use.)
There are video dimension & audio limitations for iPod. For more information on this, see
How to transfer to my iPod (& iTunes) - for video
I'm not sure about QuickTime Pro on Windows. I do believe there are some limitations compared to the mac version. However, you should be able to use it similarly with any luck. Open a video in Quicktime, Control E or go to file menu & choose Export -> Choose
Movie to iPod from drop down menu. See sample below, click attachment thumbnail to see large version.
