system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is behind the "patina" or warmth that most video footage from the 70's, 80's, and sometimes 90's? What technological advancements (aside from transition to digital) caused it to go away?
gpt
Of the 3 colors used to develop film–red, green, and blue–red is the most stable. This means that as time passes, the blue and green colors fade quicker than the red (which takes quite a while to fade in some cases). 

The video footage you are watching was on film that faded for some time before being transitioned into a digital format. The result is that the blues and greens are faded slightly (or significantly) more than the reds, which is why the footage has a "warmer" color.