I may be a sentimental old fool, but 8088 Domination genuinely brings a tear to my eye. The perfect timing of the "I WAS WRONG" reveal (i.e. "Oh look, this IS graphics mode") and the familiar breakdancer appearing - greatest callback in demo history. I really hope the room erupted into applause at that moment - just perfect.
It can't decode MPEG 4 real time, of course, but machines of this class are more than capable of streaming video.
ZX Spectrum streaming with a network interface (~3.5MHz Z80):
https://www.youtube.com/watch?v=ooi9rpx6ECM
Commodore 64 with lots of RAM (~1MHz 6510):
https://www.youtube.com/watch?v=IXLv7UosQXs