No the OTA is from samsung so if you have root you cannot use it.Isn't flashing the ota rooting the phone?
I find it hard to believe the beta program was UK specific since they pushed specific carrier updates for the US carriers as part of the beta. They wouldn't have put the beta app in the samsung store for US users if they didn't want us testing it as well.
Even the people who have flashed the ota without being part of the program have the samsung members app loaded asking them to provide beta feedback so it's all the same.
Not sure what error your getting but I'm fairly confident it's not because the US users are downloading the beta that is completely different from a UK version.
I was just on XDA and all the topics I'm seeing are for rooting the phone in order to get the update. The site is really cluttered up. If someone can post a link to the OTA for Spring that will help a lot.
You should not have to root to flash an official version. I can't comment on the SD card method because I haven't done it, but using ADB with the phone's Download mode, I previously flashed the US unlocked firmware and then back to the Verizon firmware. I also rooted for a while, but that was after flashing the unlocked firmware.
You do need to be rooted with unlocked bootloader to flash custom ROMs, but the beta isn't a custom ROM.
The problem is that I can't find the Beta OTA... All I'm seeing are roms and to root the phone. I wanted to try the SD Card method because I have never used Odin before. Everyone saying it's really easy just downloading the file or files to the SD Card and just install it during booting up in recovery mode. And I'm seeing something else when going on XDA and YouTube for guides.