I'm in Germany and connect to Xbox Live using a German IP, but I've always used a fake address so I can see the UK marketplace.
(Disclaimer: This is because the German market place filters out any content that is rated 18+. I know this is not strictly legal, but I'm an adult and I can decide myself which content is appropriate for me)
The problem is, at some point in 2007 or so MS added an IP filter, so even with my UK account, I still cannot access all content (for instance, I cannot download Duke Nukem, since it's on the index in Germany so it's blacklisted for German IP addresses). The same is true for video on demand, I cannot watch anything (not even cartoons!) on the Zune market place.
But does that extend to games on demand, too? I would try it myself, but you must get past the payment screen in order to download, and even though I'm sure I wouldn't get charged if the download is inaccessible, I don't have enough MS points right now to make the purchase, so I cannot try.
Has anyone here ever tried accessing Games On Demand from other market places?