A boot that fits right will be warm. The dude as Ski Deals is an idiot. The venting is that similar to goretex (in theory). Let out steam, keep out water. Designed to keeps your toes drier, and thus more prone to staying warm.
Warmth concerns with boots is really a thing of the early 2000's and beyond. If you get a modern boot that fits, don't wear cotton socks, and keep your core warm, you'll have warm feet. Same works for gloves in fact, keep your core warm and a mid thick "park" glove will do even on -20 days.