In the video for Christina Aguilera’s song, Ain’t No Other Man, there is a moment around 3:40 where there are some trombone players in the shot. The video actors are doing what people tend to do when picking up a trombone for the first time: grabbing the second slide brace with a full fist.
I have attached a side by side comparison for the benefit of all those who don’t want to be caught “fisting” their trombones. The proper technique, as demonstrated here by Bill Watrous, is to use the right thumb, index, and second fingers to manipulate the slide.
The slides also are reversed, so that they are being worked with the left hand (fist in this case). I am guessing, and you might too, that the whole purpose was to just show the brassy bell and not the extras’ heads, to give the impression that the synthesizer production was actually a cool brass backup combo. It probably took a few takes to establish that, and the director called for the setup. “Yea, can we have the trombone players with the bells on the other side?”