maybe there is more going on here but it's relatively easy to make a text post processing shader and apply it to anything, 3d scene, a video, etc...

https://post-processing.tresjs.org/guide/pmndrs/ascii

https://forum.babylonjs.com/t/ascii-shader-using-glsl-postpr...

https://threejs.org/examples/?q=ascii#webgl_effects_ascii

https://fwdapps.net/l/asci/

https://codesandbox.io/p/sandbox/ascii-postprocessing-n628p8...

https://www.youtube.com/watch?v=NxeRcnLr0ko