Disclaimer: I work on YouTube's video players. But I don't speak for the company in any way (this is my personal account on my personal computer on my time off from work).

If I understand this correctly, it's worth clarifying that "60% less bandwidth" is for the website host, not the client. Which yeah, is expected if you're using a P2P protocol to offload your bandwidth costs to your users. But it's not a 60% bandwidth savings for the consumer.

I know some might think that's obvious but it's always worth clarifying whose bandwidth you're talking about.