Movie in Movie

Hi folks.

I have done this before, but for the life of me, can't figure it out now.

I have a movie of a spinning object. I want to put it over a black background, but resized top right.

I know I'm using a black generator, but embedding the small movie, I need to know how to accomplish.

All advice apprecaited. Searched in here and on Youtube and "movie in movie" doesn't come up with anything, nor other searches I have tried. So I'm stumped.

Cheers