You can use a 'Video Stabilizer' - so called. These are the same things your dad used to copy VCR tapes in the eighties. Not all commercial tapes have protection.For those that do, the video is fed from the tape player to the unit thence to the recorder. I have a unit identical to the one on the left - only mine was purchased from Radio Shack fifteen years ago. http://www.checkhere22.com/stabilizer/ P.S, the link is for information only - i have never done business with this company. You can probably find the same thing on eBay.
I had good luck with the Video Magic/ULTRA from http://www.stardevelopment.com for copying vhs to dvd.