For any difficult technique, slow and steady wins the race! Turn the metronome way down, or slow the video speed way down. So it's almost too easy. Then do the action over and over, get those reps in! Develop that muscle memory. Then, after 5 min, speed up the metronome/video a little bit (10-20bpm). Repeat. Carving out that muscle memory at the slow tempos will enable you to play the technique at higher speeds.