I just learned by trying to play Primus' DMV until my fingers started to do it.
You don't really need an instructional video, you'll know when you're tapping when you hit the string and the right note comes out

One tip I can give, though - the part of your hand you use for tapping is the muscle between the hand and the first knuckle of each finger. If you play piano, you use the same muscle to push the keys.