I’m home now and I’ve tried.
It wasn’t working before, because the original video was in a group. I think it was copying all the info from the group.
Now I de-grouped the origin video and de-grouped the destination video.
I copy and paste the attributes.
And it copies the mask, but since my destination Video is shorter, and the mask key frames on the original video are on the end, they are not being copied right!.
Any ideas how to solve this?