Ha ha it's just a sign of the times, that site is using HTML5, and well if you though playing videos in Flash via youtube try playing those lowly videos with the HTML5 codec....HTML5 IS a very CPU intensive way of doing things. It just shows both how powerful CPUs have become and also how inefficiently we use that CPU power these days. The antithesis of Amiga haha
The PC hardware isn't the issue, every graphics card today has a fall back legacy standard SVGA modes for 256 colours but the only way to use them is to write a bespoke Windows/Mac/Linux program to display the images full screen with native colour palette cycling on such a screen, just like Dpaint does on ST/Amiga/PC. It's just a way of making it format independent so people from just about every OS format can view them today.