Ok, so sources elsewhere in the industry generally agree that there is a 5 to 8% lumen loss when shining through a pane of glass. This rises fast if the glass is at all dirty, so keep 'em clean, kids! So on this score, he's not too far off.
On to the 15% efficiency loss claim for air cooling; A 1000W bulb is putting out 3500 BTu per hour; it's gonna take a freakin' hurricane blowing at subzero temps to cool that bulb enough to get it to spectrum shift. I do recommend people use room temp air to cool their hoods, mostly to ensure consistency, and so they're not pouring AC dollars down their vent holes, lol. I run ochos- magnum xxxl hoods with 8" vents- and an 8" maxfan at the end, pulling air through and out. I remove the majority of the heat, will guess about 2/3 of the total heat output of the bulb, with this aircooling. Lumen loss/spectrum shift from aircooling? Negligible. Don't believe me? Do the math...
If you look at the guys running vertical bare bulb rooms, you'll see a lot of them have fans blowing directly on their bulbs so they don't have hotspots in their bloomrooms. Whether you blow through a hole or just blow, you're still moving air across the bulb's surface, so this should be a wash.
Here's the difference; the bare bulb guys have to run AC to cool the entire 3500BTu/hr of each 1000w bulb; the aircooled guys, just 1/3 of that. That power savings alone more than makes up for the lumen loss of glass in a sealed hood.
Now here's where the dude in the video missed a big opportunity; it turns out that different reflectors vary wildly in how efficiently they reflect light downwards onto the working surface. Xtrasun style hoods, the smaller ones, SUCK because the inner sides are too steep and only some of the inner surfaces are reflective. The wide footprint magnums, raptors and the like are far more efficient hoods than anything this side of an adjust-a-wing, and then only because of the glass issue. If the dude had focused on that, he would have made a much stronger argument. Hard sell, questionable facts...