Down Syndrome User Friendly UIs

My 40 yr old down syndrome brother knows how to use YouTube on the iPad to watch an old anime series. he tends to watch stuff he was more cognizant of in his younger years. Revolving around old memories seems to be an important part of his world. Youtube's 'Other videos like this' feature allows him to just tap with one finger and always get to another episode. I've heard parents tell me their 2 year old knows how to use YouTube on the iPad, but seeing it first hand with my brother is so much more moving. With an ipad, the world is open to my brother. He can discover things where previously he might just rock himself in the dark or sleep all the time from boredom.