What i did for the US was simply login with my usual amazon credentials from amazon uk, on the US site. Credentials are valid everywhere. Then just click on "start trial". I couldn't get the "prime video only" to work, but it worked once i selected the normal one. The trick then off course is getting it to work with AnyStream. You'll need a PAID VPN for that, as most vpn providers don't offer "content unblocking" vpn servers under free plans (as well as usually restricting speed on those). After trialing 2. I signed up for a 1 month with ExpressVPN. I plan on renewing my ExpressVPN in a few days.
Assuming your current region settings in Anystream are anything but "United States", so for example "Other". If you want to then access US Prime, you'll need to
- While anystream is active, set the region to "United States"
- Shut down anystream
- Start your VPN (in my case, ExpressVPN) and pick a server in the US. I consistently go with "New Jersey 1"
- Restart AnyStream, and click the amazon tab and login
The VPN connection needs to remain active as long as you're downloading. And if you plan on grabbing something from your normal region after you're done with the "foreign" content. You'll need to make sure your anystrream region is set properly prior to disconnecting your vpn
So for example in my case (when i wanted doctor who from the US)
Anystream was set to "Other" (my normal region, as i'm subscribed to primoe uk but offered content available to BE).
Open AnyStream > change "Other" to "United States" > shut down AnyStream > enable VPN and pick USA server > start anystream > login to amazon USA (you only need to do this once, even if you switch regions in between! AS will automatically load the proper prime region display) > download away > few days later an epsisode comes out on my normal region so > switch anystream region from "USA" to "Other" > shutdown AnyStream > disconnect VPN > restart AnyStream > download that episode the usual way > switch anystream region back to "USA" > shut down AnyStream > enable VPN > restart anystream.
It's a bit of a dance but summarized
Open anystream > switch region to the one the content is available > shutdown anystream > enable/disable VPN according to the region > restart AnyStream > download
One thing to note though is that you need to make sure your Antivirus solution doesn't interfere with the secure connection. In my case Avast's "Real Site" module caused a DNS leak which amazon WILL detect. Resulting in "problematic" access to the US region. Once i resolved that problem (by simply removing that avast module), i've had no problems at all accessing US prime trial.
The trick however will be to actually sign up for the paid one. Channels (like britbox, required for doctor who) require a US address and payment method. Which is where "US Unlocked" would then come in. I'll know in a few days when my trial expires if i'll be able to use it to sign up for "prime video only" instead of the "full" one. Prime US certainly didn't have any problems charging the virtual card for the britbox subscription.