I saw this video shortly after it was posted in March of 2013, and four months later, with zero musical background, I purchased a violin and started to teach myself to play. I keep a logbook of how much I play, and what I'm playing, and what works and doesn't work and other notes on things I've discovered along the way. I'm not great, but by my reckoning, I'm good enough. In my entry for 18 August 2013 (a Sunday), at 8:37
am, I wrote:
"Played Tetris 2x, for variety. It is much smoother -- I remember all the notes! It was one month yesterday since I bought the violin."
"Tetris" doesn't refer to the video game, but to the song played in the video game, a Russian folk melody known as "Korobeiniki". In the next entry, for Monday the 19th of August 2013, I note that I practiced playing the Metal Gear Solid 2 Theme in addition to practicing the Tetris Theme, and also I note the total amount of time I had been playing the violin up to that point.
My total: 20 hours.
So I was twenty hours in, and I was playing at least two different songs. I wasn't that great, but I was good enough. My intent with this post isn't to brag on my mediocre accomplishments, but to point out that learning new skills, even complex ones, is something anyone can do, with a relatively small investment of time and effort. Twenty hours isn't much. A half-hour a day for a month and a half, skipping a few days.
Sitting around watching other people do stuff might be entertaining, but to me, learning to do stuff myself is more entertaining and far more rewarding. I will never be Hilary Hahn or Jascha Heifetz, but I'm good enough, and being good enough is good enough.
tl;dr Don't convince yourself you cannot learn new things, and if you do believe that, it would only take about twenty hours to disabuse yourself of that notion.