system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a paused YouTube video not retain the same video quality as when its playing?
gpt
YouTube compresses video fairly aggressively. One of the ways this manifests itself is blocky artefacts. Normally these artefacts will blur across frames, meaning when frames are viewed at the normal speed you generally don't notice the artefacting as much, but paused only artefacts on that individual frame are seen, resulting in an apparent drop in quality.