Russian passenger Yevgeny Kayumov filmed the embarrassing incident on the upper deck of an A380 while flying business class en route to Dubai.
Tagging Emirates on his Instagram account, he wrote: "I accidentally filmed this video, and didn't even notice this moment at the time, pouring unfinished Champagne back into the bottle."
He asked the airline: "Is that normal practice Emirates?"
Responses from his followers were divided between complaints he might have cost the crew member her job, to one who said there was "nothing wrong" with putting the bubbly back in the bottle.
"She should be commended for not being careless," went on the comment.
"Someone else could have simply thrown the excess in the sink - which is a total waste.
"Maybe it could have been more elegant if this action is done in the galley instead of the open bar.
"But good for her and good for @emirates to have responsible crew like this lady."
However, this is apparently not how the airline saw it.
"Emirates always strives to provide the top quality service," an airline spokesperson told Moskva City News.
"Actions recorded on this video do not comply with our quality standards.
"We are currently investigating the incident."
The incident appeared to involve unconsumed complimentary Champagne handed to passengers after they board the aircraft.