Thanks to TLS, Netflix and Fast are indistinguishable. All your ISP knows is the IP address you’re talking to. They’d only know that you visited Fast in particular if you were using your ISP’s DNS, which you shouldn’t be using anyways :)
It's indistinguishable from an protocol perspective, not a data analysis perspective. Or to put it more practically, if a large data stream from Netflix lasts more than 10 seconds, it's video.
Makes sense, networking was never my strong point. To be fair, alot of people will be using their ISP's DNS, but at least this is avoidable, even if you have to specifically take steps.