Wide mix is better mix? Really? I kind of lost the feel of this video at that simple statement because there's no context.It then says this is the Haas Effect = it clearly is not. The Haas principles are to do with sound localisation and multiple arrival times, so with short delays, two separate sounds can be identified as a single sound and localised to the stereo field placement of the signal that arrives first. Applied to this drum sample, if it was a 'Haas effect' then it would sound like it came from the left (or right) channel, but with extra depth and width, but from a certain precise location. Then the video moves on to adding wet deep reverb - it makes the sound bigger - as in as if in a bigger space, and the example is a huge space - but it adds no width - just the big flabby reverb.
I don't think the word 'wide' is the right one here at all - all the effects are well known and add extra space, depth, loads of reflections, phasing and flutters - but width? Not a word I would use. Width is dependent on where the speakers are, and often goes badly wrong with headphones. Depth and filling the sound field with reflections is NOT adding width. Taking a snare or kick sample and delaying one is a great tool (and a very old one) to thicken a thin sounding percussive sound. Nothing new here I'm thinking? I don't like these videos because people who are just starting off will learn this delay and pan technique as a 'widening' tool - and it is not. Thickening and filling is VERY different from widening, where the only way to make something go outside the width of your left-to right speaker panning is by adding polarity shifts which get detected as sounds being in places outside the two speaker's left to right field. Those bizarre tricks that can sort of make a sound appear to come from behind.