Well, that probably depends on whose locks you're trying to get around. igrigorik noted that the proxy does pass along the user's IP address in the X-Forward-For header, which could be used to preserve a country lock.
Who will actually do that? I can only speculate. I'd expect Google video sites to pay attention (they tend to be pretty technically savvy in implementing their country blocks). On the other hand, I suspect most non-Google sites to not pay attention unless the proxy usage becomes large enough to notice (or unless they're already triggering off of X-Forward-For for other proxies and the like).
Who will actually do that? I can only speculate. I'd expect Google video sites to pay attention (they tend to be pretty technically savvy in implementing their country blocks). On the other hand, I suspect most non-Google sites to not pay attention unless the proxy usage becomes large enough to notice (or unless they're already triggering off of X-Forward-For for other proxies and the like).