Ask HN: Is it legal to crawl/index YouTube? Does Google try to stop it?

They have a sitemap, so i reckon it would be ok but honestly it would be better to use the youtube api.

Nothing illegal about it.

They may have some opinionated terms of service but i don't think anyone bother reading it besides their own lawyers

It is legal but ToS may prohibit it.

Depends on where you live.