Hi

I tried the link on my daughter's Nexus 7, which is still pretty much as supplied by Google, and it works flawlessly.  The page renders correctly and the video plays when clicked.  It works because it is a youtube embed and so doesn't need to rely on Flash to play the video.  Flash videos will NOT work on a stock Nexus 7 because there is no Adobe Flash support for Jelly Bean.

I hope your son enjoys his new toy - I can recommend a good kid friendly case if you do go ahead...

My unexpected surprise was that I ordered and paid for an 8GB unit but they sent me a 16GB one - certainly not complaining though!