Hey! It looks like you are really getting the movement down. Vibrato takes time to in your fingers… but the good news is that once it’s there, it only gets better and better! Really think about using gravity and the weight of your arm to rock your fingers back and forth. The harder you try to wiggle your finger back and forth, the tighter the vibrato gets and the harder it is to play, so really relax. When I teach, I usually have my students do a tendon exercise that also helps with getting an even wave length. Uneven vibrato is not something you don’t want!
If you’re interested, I’m teaching lessons through this site and I would be happy to work with you on vibrato!