I will update this with images when I'm out of school! Here are the steps-by-steps I did:

1. First, I downloaded this green screen curtain video.
2. Second, I converted it into a GIF via Ezgif
3. Third, I removed the green part via effects. It's the "replace color with transparency" option! Just get the green color, add some fuzz so that it gets all of it, and then save.
4. I add it onto my GIF template via Photoshop and voilà! Finished!