I did some more testing. I can't use the adobe flash player to play youtube videos
because it requires MMX (I am working on an MMX emulator but it has lots to go and will be slow)

But on Windows 2000 I can play 144p youtube videos actually quite smoothly
thanks to the windows port of youtube-dl (How did they roll a python script into a windows
binary anyway?) and mplayer

Mplayer can actually be quite fast on old machines with the proper tweaks

--edit---
To clarify, the videos were playing on the newer 486DX-120 of course
not the 486DX/33

Oh, man, so much nostalgia. Thanks for this post. I remember one must fall 2097 on 3.11... Good times.

I wonder if anyone is still using the old Lynx text browser.
Long time ago I had an old IBM XT with its 256k of RAM on board and two 256k memory boards. There was a small exe which would extend base memory from 640k to 720k. I had an intel 10b2 nic and had to load the drivers and an ip stack for dos then connected to the 10b2 port on a little 8 port hub and was able to get to the internet from a DOS based web browser.

Sadly when out house finally sold I had to clear out quick so I left it sitting by the curb