It doesn’t make much sense to me – crop implies that you have to lose the sides of the picture, then the vertical squeeze implies changing the geometry of the pictures… however, what I think they might mean is putting the 16:9 image in a 4:3 frame in “letter box” style, i.e., with black bars top and bottom. I used to do that occasionally when it was SD 16:9 and the client wanted to view stuff on a PC with an older media player that didn’t recognise stretched pixel aspect ratios, but 1080i is square pixels (so the issue of displaying non-square pixels doesn’t arise) so it’s only a guess.