Replace green with video

[silversmith]

I wish to make intro slide of MGM lion - replace the king of beasts with my kitty. I have the clip with green screen for the kitty clip. How do I replace the green oval (chrome key) with my kitty?
Many thanks. Peter

[Riekelt]

I was making some screen dumps but I thought Youtube is mostly a big ( and better )help.....

so I think :
https://youtu.be/POtF2TDOG0s
is a nice tutorial for your question.

Good luck ! ( where can we see the result ?? )