MacPlusDancer
At long last, a macOS-native version of the Microsoft Plus Dancers from 2003. Thank god.
Backstory
I posted a tweet that went viral, and it just snowballed from there.

Sam Henri Gold
@samhenrigoldDetails
When I decided on a whim to port this to Mac, I assumed it was going to be trivial. Copy the files, make a transparent window, end of story.
The way the original Dancer program worked was slightly more complex. Since it was the early 2000s and you couldn’t just burn disk space on transparent videos, each dancer shipped as two videos: the dancer on a black background and an alpha matte.
My first thought was to just…make it a transparent video file. But even 20 years later, transprent videos still take an absurd amount of storage space. Unfortunately, this meant it was time to take a trip into AVFOUNDATION HELL.
Ew.
From there, it was quite straight forward. Set up a model to handle the dancers, add in a menu bar picker to keep the window chrome clean, then play the selected video in a little, draggable, transparent window.