Who ever said it wasn't good with humbuckers? People talk some nonsense on forums. I don't think I've ever used an amp that didn't work well with singles, p 90s, or hums when properly eq'ed.
I've played a few amps that don't work well with humbuckers. Mostly older amps or clones of older amps. And it's not ALL humbuckers either. The problem isn't the humbucker itself, it's the impedance mismatch between the amp and pickup(s). So it all depends on the output impedance of the pickup and the input impedance of the amp. Even on my 5E3 inspired amp that doesn't generally like humbuckers, there are some humbuckers it gets along with just fine. All that clip proves is how those particular pickups sound through that particular amp. I've never played a Dr. Z Maz, so I have no idea how it reacts to various pickups, and thus won't comment on that amp. But as a general rule, general rules are generally bad rules.
My old Maz 38 Invasion doesn't get cranked up much anymore but last Sunday I plugged my R9 w/ Wizz PAFs straight in. I cranked the master up and just sat right on top of that cab for a couple of hours letting those good vibrations rip through me. That's a tone even a blue bellied devil would like.
For distorted tones (like the ones in the vid) I think the Maz sounds great with humbuckers. I always got great crunchy rhythm tones from it.
For awhile though, I was frustrated with my Maz 38. I was having trouble getting the kinds of clean tones I was after with a P90 equipped guitar. The amp seemed too dark and a bit boxy.
Then I remembered to adjust the EQ with my ears and not my eyes and all is well now.
I love my Maz with all pickups. I setup with buckers and I'm a set it and forget it type, so I do have take the tone knob back a notch on the Strat. I sounds great in any setting I've tried.
Before I bought, I definitely read that it was a single coil, and particularly, a Tele amp. Couldn't be further from the truth ime.