I agree 100% about switching to an ad-supported methodology as a fallback plan. Advertising revenue quickly exceeds 8$\month given the # of hours people watch. So if you can't manage to get a real credit card, or are otherwise willing to stare at ads to save a couple bucks. Have at it. I would design it so that you choose between free or paid, and when you cancel you really just drop down to the ad-supported version. Not sure how that plays with licensing though.
International gives them the opportunity to test such a thing without excessively damaging their brand elsewhere. 'Oh this is just an idea we had that's particular to Uruguay's particular economics.'