Its was a handy feature that I used rarely but when you needed it was there. Google claim the internet is more reliable so it was a.pit of date tool.
Thing is, too many companies redesign thier website every year that many useful pages just get lost. It can be rather annoying when you finally find a Google search that has the snippet of text that looks almost exactly what you want the it is rather annoying when the site opens on a 404 and the info is lost.
Got bored on that YT video, I guess it doesn't talk about the cache, just another crazy idea of what the internet should be.