There's a line in this documentary that tells us that moth-watching is a waiting game, and that it requires patience. Well, so is a film about them - and for much of this we don't really advance much in our search of the reclusive hawk moth in the forests of the Himalayas. When it does come alive, though, it's fascinating to see the sheer variety of flying nightlife their screen attracts as they try, quite meticulously, to position it to attract these creatures that are drawn to the light. The people here actually add very little, indeed I could probably have done without them altogether.…