Can you drag supply crates?

Seen clips of people being resupplied and it looks cool as fuck, but obviously the heli needs to drop them in somewhat of an open area to not risk the chopper.

Can you drag the supply crates away from the dz or are they fixed in place? Also as a side note, do they have momentum when dropping from the air? Ie if you are flying forward when released do they continue to travel forward or do they sort of drop straight down from point of release?