No data but I'd assume YouTube's biggest pull is people young enough to hate cable but old enough to use YouTube often and have $$ to pay for the convenience
https://help.amplifi.com/hc/en-us/articles/360037903234-Tele...
Can't speak as to whether the performance of a router's hardware is enough for VPN together with two streams of video.
These days all the cool kids are using WireGuard[1] though. I don't have a link to a handy installer and setup guide for that but they do exist.
Using a Pi 4 with gigabit ethernet makes a big difference over older Pi hardware.
"you can enjoy up to 250 live TV channels and up to 30,000 On Demand TV shows and movies when you're connected to your Spectrum Internet WiFi network at home. Plus, when you're on the go, enjoy up to 150 live channels and up to 20,000 On Demand titles anywhere you have an internet connection"