Perhaps you are referring to this video [0] by What's Ken Making which goes into detail about the advantages/disadvantages of both software and hardware emulation?
At 13:43, he demonstrates a couple of snes games with effects that don't work well in software emulation (along with what the effects / game mechanics should be on original hardware). At 22:25 he shows these same games running on FPGAs (analogue pocket, mister) and behaving correctly, just like on original hardware.
As an aside, if this isn't the one you were referring to, it's still an awesome video by an amazing creator; I'm a big fan of this stuff after discovering it on accident. He gives a nice introduction to FPGAs in this same video.