The Ted Talk video is problematic. Maryam Mirzakhani was a famous math prodigy. She started specializing in math and science from an early age. You can read about her here:
en.wikipedia.org
You can still achieve an insanely high level in math if you start late. That is you follow the standard curriculum then focus more on it starting in high school. I will agree with that statement but the example he used in the Ted talk was a bad one.
The examples of musicians were also semi nonsensical. At the club where I coach, there are instructors from Julliard and professional musicians who regularly perform at Carnegie Hall that also play table tennis. All of them have told me they can hear the difference between someone who started playing their instrument at 10 and someone who started at 4 or 6. I was shocked to hear this. One teacher said it was sad because she knows how badly people want to be high level players but no matter how hard they try, they missed a critical window in their development that prevents them from being at the highest level. Perhaps in some genres of music it doesn't matter much when you start like rock, but if you are going to play classical music in an orchestra or win competitions you had better start early.
Why is America losing to China in table tennis? Kids in America play sports nonstop. Some take table tennis quite seriously at say 14 but don't make it on the international stage. If early specialization doesn't work, why has China pretty much dominated for what seems to be forever? Why is Japan encouraging people to start playing at age 2 these days?
Give me a modern example of someone in the top 10 who randomly dabbled in table tennis then at age 14 became serious and made it to the top 10 or 20 or 30? In China there is a word for the 14 year old dabblers: retired. If you aren't 2600ish+ at 14, you are sent packing home. Maybe you can bribe the coach to be on the province B team if the coach runs his team that way, but as far as the A team goes, your career is over.
Some sports you can start late. Some activities you can start late. Table tennis is one sport you simply cannot start late if you want to be world class. It is like speaking a language. If you want to be completely fluent you had better start learning at a young age.