How to apply alpha channels on videos?

Support Basics & Interface
1

Hello,

Is there a way to apply alpha masks on parts of a video in Blender? For example, in this YouTube tutorial that is about another program (https://www.youtube.com/watch?v=qOhDErn36J0), the person imports a non-alpha video and turns it into a alpha video with a moving solid object. Is there a way to do this in Blender, i.e. altering parts (such as the background) of the video to become alpha?

If not, what other free easy-to-use software would you recommend?

2

So apparently I need to use another software for this?

3

I don’t see anything in that video that you couldn’t do in blender.
You can remove the greenscreen in the compositor and convert to a mask.
I don’t know exactly what you want to do but you can put also use the compositor to a add two video clips side by side

4

Currently I want to use this for a face swap, thus making the face of a person on one video transparent and adding the other as a layer under. But I see the tutorial you provided is exactly what I needed for this, so thank you. I will try it out as soon as I have the time.