I just posted this on the other thread. It isn't about citizenship or even really residency or non-US. It's about accessing the video chat.
Anyone who registers for DAS in advance via the video pre-registration is eligible for the 2 DAS Advanced Selections in addition to the day-of DAS Return Times. If you register on-site at a WDW park, you are only eligible for day-of DAS Return Times. So there is no "only allowed 1."
As I understand it, the challenge is connecting to the video pre-registration, which is primarily accessible via the US website and only available in English at this time. That said, I have heard of people in Canada using a VPN to access the DAS pre-registration, essentially by bypassing the Canadian WDW website. I'm not techie enough to know if that is what's actually occurring or if it would work from another country.