How much more does it cost them to make their content available worldwide? Couldn’t they upload everything to YouTube and let Google foot the bill? (Which Google would gladly do.)

I don’t know whether more people would donate if they made their content available worldwide but if such a move wouldn’t cost them anything or nearly nothing there certainly wouldn’t be any harm in doing so.

Mmm. They could try it; but the only shows for which it would be easy to try it would be those for which they own the copyright. I don't know whether that would be a representative sample.