One thing that vid doesn't mention, it helps to have the joystick in neutral when you jump. I'm not sure if it's optimal or even 100% necessary to do it, but I used to have a ton of trouble hitting this NISC until I started doing that

If you're trying to play the track optimally on 150cc I don't think you want to use a mushroom because it saves more time to use it to cut through the grass on the last turn

That NISC is in my opinion the hardest to hit in the entire game (at least on 150cc). Basically the way that I do it is to try and start a drift as soon as I can while still inside the dragon so that I can get a UMT. Then like the others have pointed out, brake drift so you can hit the turn right outside the dragon as tightly as possible, which should give you time to line yourself up to hit the jump. I don't know if it's absolutely necessary to get the UMT but I've never hit the shortcut without it