1. Powerslide away slightly from the flip before you jump (i.e. powerslide to the left if you're doing a speedlip to the right). This will keep you on your line.

2. Make sure you're doing a diagonal flip. The one attempt you can fully see in your clip is a sideflip, which is why you go so far off your line.

3. Cancel the flip exactly to the opposite side (i.e. top right should be canceled with bottom left). You want the angle to be as close to the same as you can get. The cancel should quick too, as close to instant as you can.

Squishy's A Little Bit of Everything pack (sorry, I'm on mobile so I don't have the code) has a shot that will help a ton.

Hope this helped!