I'm probably not using the right terminology. I pay monthly for prime video and can access this on my laptop but not on my TV. When I try I'm told to go to virgintv.com and enter a code that they supply me with then I have trouble signing in - tells me my email isn't correct - same when I tried to change my password. I'm probably going to be a hopeless case - me and tech don't go together 🙄
If you want to watch Prime Video using a device such as a TV box, TV, game console, etc, the process is the same in that you need to register the device on your account. For VM, launch the Prime Video app, go to settings and sign in. You will be presented with a 5-6 character code, go to amazon.co.uk/mytv on a browser, log into your Amazon account and enter the code. Your device will be registered and you can now use it to watch Prime Video.