[gloryblaze]

... apparently-transparent jug ...

That is some sort of large metal roof vent. It didn't go anywhere. If you google, it remains in place on all the images where it is in the line of sight.

[rx]

Vent?   No, I don't think so. Here's both the jug and the roof vent. A different look entirely, me thinks. And in this shot the blue-capped jug, with handle, looks to be rather close to Crooks's sniper perch position.

Those Nike low-cut tennis shoes to the right of the jug are on the shooter's feet.