I would have thought that with the amount of data that DVD players work with and the integrated-ness (is that a word ?) of the circuitry you'll be very lucky if is doesn't crash completely and probably fry if you even think about it, let alone go near it with a soldering iron.
If its a direct drive VHS player you may be in luck but in my experience anything with a belt drive tends to not have enough torque to drive the motor really slowly or in reverse. It'll probably automatically shut down the second it senses something wrong with the motor speed anyway.
On the other hand, who cares?
give it a go...........
