Don't forget the other assistant to follow your assistant and give them back and foot rubs to keep them going haha. Yeah info on this lens was posted a few months ago but this is the first I've seen of the video.
Forget the assistant. You better rob a bank or hit the lottery to afford it. Than do a few cycles of roids to wield it. That lens has to be mounted on a military-grade tripod with hydraulic assist. Like what they mount anti-aircraft machine guns on. Seriously. You might need a Hum Vee to go with it. Impressive though.
meh, rather go with a canon 600mm or try to find a 1200mm, now THOSE are good lenses; and you can actually try to carry them. (Well maybe not the 1200)
if you mean why have Sigma made that lens, well its the same reason Canon made the 1200mm F5.6 and the 50mm F0.95 and Nikon making the 2000mm F11, because they can and it shuts the competition up, at least until someone makes another daft lens