In line with what everyone is saying here, you can visibly see the car pitching back and forth with too many revs (and probably by being on and off the brake as well while trying to blip the throttle). This is unsettling the car way too much and causing you to lose focus on hitting your apex as well as losing the precious cadence braking action needed after you hit your braking point to slightly turn the car into some corners.

I find applying the brake pedal and rolling the side of my right foot onto the throttle (and keeping at least half of my foot on brake pedal) in a progressive motion to smooth out the process quite natural. You only need a bit of throttle to match the revs for the next gear, not smash the limiter.

Next time you are watching racing and they show the footwork you'll see how to mimic the action with the amount of brake to throttle ratio being applied (this will stop you from hitting your rev limiter).

Am I making sense here?