It’s certainly possible to scrape data from interactions with a site directly, without using its API. This is even legal - there were no gymnastics in my response there. However, that decision has since been remanded, then re-affirmed, then challenged, and then LinkedIn obtained an injuction against HiQ which the two of them are still fighting over. So it could get properly overturned.

I definitely thought it seemed like it would be difficult to do this to offer a youtube frontend, but plausible enough that I didn’t look into it. Thank you for this. I’m looking more closely now :)

If they are using undocumented internal APIs, do YouTube’s API TOS apply to those? I checked the text of the TOS and it seems to me like it should apply; they say “The YouTube API services … made available by YouTube including …”. That seems broad enough to me to cover internal APIs as well, if their endpoints are accessible, but IANAL.

Also, the open response to the C&D seems to throw shade at the TOS saying “The “YouTube API Services” means (i) the YouTube API services” but ignores that this is immediately followed by parenthetical examples and qualifiers. The TOS is defining the term so that it doesn’t have to repeatedly add the qualifiers. Nothing weird about that. That’s uh… pretty bad-faith arguing, if I’m interpreting it correctly.

Edit: assuming you refer to the same reverse engineering points that they made above… yeah.