Level 3 in the S-Class and EQS has been available since may 2022. And the speed limit is there because that is part of a UN regulation that the Mercedes is certified for. The regulation has been updated since the release of Mercedes Drive Pilot to allow speeds up to 140km/h but Mercedes needs to recertify for that.

It is possible. Maybe the peering from his ISP to YouTube is shit/ overloaded. That was an issue for Deutsche Telekom for a few years because Telekom didn’t want to pay for better peering. With a VPN it is possible to get good peering to your ISP and YouTube and in return faster load speeds.

Even better: an antiperspirant. It significantly lowers sweat production on the applied area.