This is a computer art subculture specialising in demos, non-interactive digital presentations. These have been present since the 8-bit computing era of the 1970s, first appearing on the Commodore and Spectrum systems. Began as software 'cracking' where people would hack into the codes of games to produce alternative outcomes.
The aesthetic of demos can often be quite retro, harking back to the era of pixellated graphics, such as in this example from 1995:
The above movie also incorporates explanatory text alongside the typically 90s graphic styling.The below one, (mainly a musical piece) however, is more reminiscent of 80s computer graphics:
Modern day demos use patched/modded videogames for repurposing of existing games with level editors etc. Machinima is a good example of this. It is part of a wider range of mediums within the grounping 'video game art' which involves painting, sculpture and appropration amongst other things.