Very interesting, thanks Buster. Grunt Encouragement films can be entertaining. That American "Heavy 30" is a fine Browning creation - that weighs 7000 pounds more or less. Before the war (WW2 I mean) was over, it was deployed only in 'permanent' emplacements I think. One of my brothers carried an air-cooled 30 up through Italy, and he said it was plenty heavy enough. (He also had thoughts about the effectiveness of low stone walls when the enemy had an elevation advantage, but that's another story.)
That MG42 is the subject of a more modern article in a gun magazine I read recently. One of our guys earned the Medal of Honor for an escapade during which he carried a captured MG42 and used it like it was a BAR. I'm pretty sure a water-cooled 30 would have been too much gun.