The Chromecast team seems to be aware of the issue:
https://www.googlenestcommunity.com/t5/Chromecast/I-m-not-able-to-log-in-on-YouTube-on-my-Chromecast-2nd/m-p/182554#M19057
Same problem here: "Can't sign in. You can still use youtube as a
guest", every way I try to sign in. Reboots, unplugging and factory
resets didn't fix the problem. Sign in via the Android app after a
factory reset doesn't work either. Started after ...
I've got the same problem: it just says "Can't sign in. You can still
use youtube as a guest", every way I try to sign in. Reboots, unplugging
and factory resets didn't fix the problem. Sign in via the Android app
after a factory reset doesn't work e...
