Roulette How does this guy manipulate the returns?

I've been watching a Youtube channel called All on Black where he is doing a challenge to make $100k in a year. After two weeks he has had some bad days but most days he is making plenty to stay in the green. I don't really understand the system he is using but he seems to be able to turn his fortunes upward even after going into the negative a long way. Given that this is the game of Roulette he should be winning about half the time and losing about half the time but instead he's making thousands even after playing hundreds of spins. Can someone explain it simple to me, what is going on here?

 

Which guy?

 

The Youtube Channel called All on Black.