Why is there no easy way to set the "alpha" or "transparency" of a video clip?

[peterhoang]

This is easily done in a video editor, but the whole point of using MoviePy is to automate this tedious process.

I searched around and I can't find anything.

There's a solution to convert the overlay clip to .mov which I did using ffmpeg and then set has_mask=True...but where's the property for the actual alpha? E.g. clip.set_alpha(0.5)?

Btw, has_mask=True did nothing for me.