My preference is a jam nut. Just put another nut on and tighten it, ideally one on both sides of the connection. They use it for tie-rods on cars, it should hold the table saw.

Main advantage is it's easy to take apart, And doesn't require drilling or tapping what you have

It could work for sure, but I see two tricky parts. Strength wise, since the plastic is less rigid, you have to be careful the glass doesn't crack. The polycarb top of the table will deflect more easily than the same thickness of glass. I think really thin glass helps with this, think screen protector for a phone.

The cosmetically difficult part is gluing them together. It's tricky to get a perfect bond over the whole surface of the glass with no air bubbles, voids, or dirt.

Not really, films are also plastic and scratch easy.

But it isn't hard to polish scratched plastic (does require elbow grease). there are polishing kits.

If you wanted a harder surface, a two part epoxy may do the job, but epoxy is expensive and hard to work with.

I'd just use the plexiglass and if it scratches, who cares

If it's just capped off (no flow) there is no functional difference between reduced or not. Diameter is to allow more airflow

Edit: misread the post, I saw cap, not vent cap. Disregard

Yeah good point, it has to be insanely expensive to have enough storage space and bandwidth for all the videos. If you can't pull in enough of a crowd quickly, it would be massive losses.

Helps explain why in the last two years it feels like YouTube is doing 4-5x more adds

I suspect part of the difference is also paying content creators enough. That cuts into Google's share, if they don't give creators enough money, the content will go to other platforms