Hello,

The thing is that the agreement they linked apply to the official YouTube API (the one that you have to register for).

Invidious uses the InnerTube (a completely different “API” used by all official YouTube clients). Invidious basically acts like a web browser that access the YouTube website. It is therefore not required to agree to any TOS/policies.

All those findings where done via clean room reverse engineering (which is legal in the EU).