Classical animators, please help!

Hi all!!

I’m working on a new project and it has some classical animation techniques which I know in theory but I never used.

My boss gave me this incomplete Flash animation and I have to finish it as soon as possible. The animation has 3 different sizes of frames and a cross in the middle which I know is the center of the movie. I read that those frames were used by the camera in old times but why would Flash need 3 different frames?

In Flash when I want to do a zoom in or out, I just make the whole animation bigger or smaller. Does he want me to choose between those? Or there is something else that I don’t know? Which size should I use?

Thank you very much in advance!!