How do we get alpha channel in our video movies?

Is it possible with WMV?
So you can have Cutout Talking Avatars using a transparency Alpha channel for your widgets?

Removing all the solid background from the movie
around your character so its all alpha channel.

Videos is an index format and does not contain an alpha channel. What you can do is make a video mask in the RGB channel and plug that into you transparency. There is a video format used with Premier or After Effects that can contain an alpha but I don’t think UE4 supports the format.

Hmm. I see, so Alpha Channel wasn’t avaliable in Crazy Talk Either when I check the pic
masking options before exporting out the movie. I really wanted alpha channel but maybe we can export the video out in still picture frames, (Crazy talk allows that) then edit those frames manually to put the alpha channel in, and reassemble those frames back into a movie again. But I don’t have the software to
reassemble the frames into a movie. But Can that be done?