If a cargo plane has a crake of parrots weighting 200 lbs and they get out and fly around the cargo hole?

Mythbusters already tested this.

They put 20 pigeons in a big clear lexan box sitting on a sensitive digital scale. Turns out the box weighs the same if they birds are roosting (sitting) or flying. Why? Because when they are flying - the birds, they are exerting the same amount of air pressure pushing down to keep them in the air as their actual weight.

Now you know.

Plane does not get lighter because it is a closed system. Imagine if it were filled with water instead of air. If some fish in an enclosed crate got out and started swimming free, the plane wouldn't weigh any less either.

A crate in the cargo HOLD... No, the plane weights the same as the weight of everything inside it (including the air) is accounted for.

Only if the windows are open. If the environment is closed, then the mass of it stays the same.