Movie kill, originally means that the negatives, which have been shot, have been placed in a box and are ready to be sent for development. Mostly it means that the filming part of the movie has been completed.

Individual actors will also say I'm done when they're done filming his personal scenes. Including writers, screenwriters in the completion of the creation of the revision stage is also called kill the green! For example, "the movie that lasted half a year and went through four provinces is finally finished! You can have a good rest now".

Expanded

Source

The word "kill" comes from the pre-Qin era, the ancients wrote on bamboo slips, but the surface of the slips is oily, not easy to carve the characters, and prone to insect infestation, so they came up with a way to put the slips on the fire first. Put on the fire to bake, this process is called "kill green" or "sweat".

Later, people use a brush to write on the bamboo green, it is exempt from the knife this process, so the final draft only need to cut off the bamboo green, write on the bamboo white on the line of this procedure is also known as "kill the green".

Baidu Encyclopedia - Movie Greening