I found this trick out last night for anyone not living in the US who wants to access the PSN video store.
Firstly, log on to a US account and open up the PS Store. On the 'Home page' there is a random selection of banners, varying from games, DLC, Demos and ... full films from the PS Video Store! If a film is not one of these banners when you initially enter the store, then simply click through to anything on the store then go back to the home page, where a new selection of random content appears.
Eventually you should see a film appear - click through on this link, and you'll be given all the options to Buy, Rent, Preview etc.
Of course, this isn't a particualrly effective method of accessing films from the US store as you're randomly 'given' one to pick, and actually purchasing something is still a little tricky, but nevertheless it's still interesting how Sony overlooked something like this.
As has been discussed in the comments, please do NOT attempt to purchase any of these films as all you'll recieve is an error message ... after you've paid.