[twitter OP] This is true. Appears once a day or so, you hit OK. Sometimes during a show you're watching, sometimes while it starts up. Don't know if it becomes blocking some day...
Turns out, in my case at least, the warning was a little misleading.
It required me to log into their apple / icloud account and accept some terms, I did this with a normal browser (again non-apple) and the warning went away.
May be different in your case as I was setting up a new account for them.