masking in the editor

No, I used a motion tracking with a corner pin deformation.
Masking would just make a hole with the video behind, and it would look terrible cause it would not follow the perspective.

Did you use final cut? I am so interested in how you did the motion tracking because a while ago i made a similar piece and i couldnt figure out to do it because i moved the photo around, and then i saw your video one day and i was so interested because i had tried and failed. So i had to do something not as cool but feel free to take a look... : )
vimeo.com/931701

I used After Effect.
Apple Shake works very fine too for those kind of things.
I still like your video, limitation is good some times and force you to deal with what you have at the time.

thanks a lot!

Thanks!

Nop, no changes.