If you slow down the videos you'll see that he's all over the place, not only not in sync but showing no signs of actually being able to play the instrument or knowing the pieces, other than miming air-guitar style. He's on the wrong strings, in the wrong positions, going down when he should be going up, sliding when the sound is distinctly articulated and vice versa, etc. He can look easy and fluid because he doesn't have to actually produce any real sounds.
Relevant is TwoSet Violin's frequent debunking of fake violinists (in movies etc.), and also Nahre Sol's latest PBS SoundField video, on Editing in Classical Music, particularly the part where they do a blind test of whether they can tell which is real, the real recording or the virtual instruments (MIDI sampler). Hint: they fail a lot, even on their own instruments.
Also, the most popular YouTube video of the Beethoven Moonlight Sonata (with 170 million views and counting) is a programmed midi sampler, but yet almost nobody notices that fact (which becomes pretty obvious by the 3rd movement).