The CGA games in the video looks like you played them on a VGA system (funky purple colors and teal).
Most CGA games had a Tandy mode and that made them look (and sound) much better.
Check this out:
Pictures of the differences at the bottom
The Amiga had better sound untill the Gravis Ultrasound (midi in general) came out, once the Soundblaster 16's came out even sound affects were better on the PC.
VGA pretty much owns AGA.