Yes. The whole problem here is that these are gifs - tiny little silent movies (which is probably why I love them so much) - which leaves out the all-important sound effects and snippets of music that invariably accompany these feline follies.
But they're still fun to watch. The green screen technology is something I know nothing about - as with everything else, I "borrow" what I see around me (most of which has been replicated thousands of times already). It's just kind of fun to muck around with these things.