I think a bit of perspective on this clip - first it was a very short TED talk - only 3 mins and was from a session with a lot of speakers (you can see them in the background at the beginning of the clip). It was therefore part of a series of talks and in context it had to be short.
He made the point that his fusion reactor was not producing more energy than was being input - so nothing extra-ordinary there - but that the process produced by-products that he could use. The main point was that he did this in his teens - starting around 12 years old and having working reactor at 14.
The two points he made was that 1. the future is fusion (yet to be achieved) and 2. children can contribute valuably. I think it was meant to be light hearted and highlight his achievements - especially for part 2. It was too short to go into detail for point 1.
So, whilst I agree he may come across as arrogant - I think that's more a feature of the format and time constraints. (I think he has the right to be arrogant given his achievements ... but he didn't come across as arrogant to me - I took it as someone who was stating his achievements and sort of saying 'see what a kid can do'! )
Mel, I hope you can see it now.
At least, I'm glad others found it interesting too!
Cheers,
Shafique