I don't think it will be a problem with TM because is not like canadanationalbank.net or usnationalbank.net it's just national-bank.net far as I know on this site could be information and news about national banks across the world and I don't see any trademark issues here.
If I can bring national-bank dot net on the first page of google for "national bank" keyword how much you think it will value then ?? the same for free-download dot us but with this it will be harder.