DVDs are encoded with a region code. The USA is part of region code 1, whereas Europe (including the UK) is region code 2. The commercial DVD player specification requires that a player to be sold in a given place not play discs encoded for a different region. So chances are, the Prime Minister won’t be able to play the DVDs when he gets home (unless he can find a region free DVD player).
I have a zero zone DVD player which means I can play DVDs from anywhere. The whole thing is nothing but a monopoly, plutocrats divvying the world up between themselves. I live in Australia but can order anything I like from Amazon etc., America or U.K.
I would imagine that the No. 10 Downing St. would run to this, although it doesn’t make the gift any less thoughtless, classless and just generally insulting.