I remember when I got a 1080p monitor and watched some slightly old content (~480p) on it. The experience was very lackluster. Now I'm getting a similar feeling with a recently-bought 4k-capable laptop, and watching 720p content that looked perfectly fine on the 1080p monitor. I don't even want to think about the 480p archives. Almost makes me not want to upgrade devices.
PS. I quite distinctly remember the point in time when I finally said my then desktop machine couldn't move video, and it really was time to consider an upgrade ...
(My 500 Mhz K6 II - DAE remember those AMD chips? - had finally become too slow. Video was 'unstoppable' ...
