Superimposing a whale to the background

Hello everyone, for one of my projects I need to... like... take a whale of another video and superimpose it to my actual white background. I need it to float over my screen but I don't need it to be completely seen, it is not necessary, you just have to guess that there is a whale floating over my background (which is egg white color). So if you could see its silouette would be fine. I've tried to overlay a whale video and then tried all mix modes but any gives me the effect I'm looking for, and also, I wouldn't be able to place the whale wherever I want in the screen... Don't know what to do. Any suggestions? Thank you so much 

You could  duplicate the video and mask in the whale.
You can also take a frame of the video and export it.
Isolate the whale with a photo editing app and save it as a PNG.
Import the PNG image into FC.