Ubiquiti is/has been a big sponsor of theirs, they just grab Mikrotik products because they are cheap and fit different needs (like 100gig where ubiquiti doesn't have anything to compare)
On top of that, they have a mish-mash of hardware because they take what they can get for free under sponsorships, and honestly, if it does the job... why not?
On top of that, for any high level stuff they seem to rely on Wendell at L1 techs, and he probably has his own opinions on vendors etc so that probably also influences it. They even mention in the video how cheap the switches are, and that'd be the main driving factor behind them being 'featured' (they don't really review it at all)
Cool to see though, and im a bit miffed because I moved from a company deploying Mikrotiks everywhere to a company using Juniper (and paying the price for it :/) so im not getting my mikrotik fix as much. 100G would be nice.