Best viewed at 720p. (no audio)
The original Macintosh computers had a resolution of 512×342 and could display each pixel as either white or black. I converted a 720p video to 512×342 with 1 bit color (b&w). I then added a border to bring the video resolution up to 1280×720 (720p). When viewed at 720p, you should see approximately what it would have looked like on an original Macintosh if the Mac could have played video. Unfortunately compression algorithms used by YouTube can blend the pixels so you may not get the desired effect.
Original video is here:https://youtu.be/RabEMoT2V5c
Some Macs with 512×342 resolution:
Macintosh 128k
Macintosh Plus
Macintosh SE
Macintosh SE/30
Macintosh Classic