There's a lot of good stuff on the internet. More information than we had access to as kids. Better to raise them to be responsible, well adjusted humans than to shield them from reality.
Some develop advanced reading proficiency well before that, and the more they read the more likely that is to become the case.
Every child is different, but the more you assume they can't do certain things, the more you'll find that to be self-fulfilling.
(That said, that makes an argument for extensive access to reading materials, not videos.)