It's pretty easy if you have the right tools. I do it all the time with my ExpressVu PVR to get Oilers highlights on the website.
I use basically an older version of this product:
http://www.adstech.com/products/USBA...d=USBAV-191-EF
Use RCA cables to connect the device to the PVR and then plug the USB into your computer and capture. It saves the clips as MPEGs and you just do what you want from there.