This one is not too difficult to explain. You take a RWD sports car, fit it with some stiffer suspension, a roll cage and a "muffler delete", then wait for that magical moment just after it finishes raining. That's what the MX-5 owner in this video did, just a few minor modifications and he was ready to go drifting. The MX-5 is very accommodating in its willingness to get sidewise, and the owner seems like he has probably practiced a bit. Probably a good idea if you plan on drifting on public roads.
Oh, and the owner is a little person. We mentioned that, right? Small car and a small person, it makes a lot of sense.