Are planes safe during COVID?

Good video. I read about that Air Alaska flight probably as soon as it was published -- the news didn't mention sitting on the ground with the ventilation turned off.  What I did learn shortly after the first news of the paper was that the only way this investigation was possible is that all the people on the flight were somewhat easy to contact. A typical lower 48 flight would've scattered the passengers in every possible direction. The implication being that this is happening all the time. 
The value of this video and these investigation emphasizes how little we really know about transmission. (If you read sources about the Great Plague of London 1665, they all begin to touch on germ theory which wasn't widely accepted for at least another 200 years. Social distancing was quickly adopted. The sad aspect is that things they knew to do 350 years ago we in the U.S. refused to consider until Covid was widely spread. It's shameful.) 
Here's an odd but related factoid. My bedroom, about standard size 11 x 13'. When my girlfriend and I have the door closed and the window AC unit running (on recirculate - not sure it does anything else). After about 6-8 hours the CO2 ppm rises to about 1100 ppm (this is with my meter calibrated at 400 ppm, which should actually be calibrated to the new world standard of 440 ppm. I have an Amprobe CO1-100 CO2 Meter. A very nerdy thing to have.)  I notice the air is a bit stuffy at about this level  (1000 ppm) -- most people seem not to.  
I also notice that around me, windows open, but no fan blowing I can get readings of 450 to 550. I assume this is just the CO2 I exhale that just sort of hangs around for a while.  CO2 metering is how indoor air quality is measured. It's what they check at the gym when the fans are running and why they might add more.
I think I also notice that when a room is stuffy people don't think as clearly, but they also don't seem to be aware. Hot and cold they notice. And in very old people, some that I know have been diagnosed with some degree of dementia, when they're on oxygen the dementia seems to almost disappear. (But not Alzheimer's).   I've always been a fresh air fiend, to borrow from Paul Theroux. 
And I've always worried about air quality and flying. I returned to Los Angeles from Hong Kong on about February 7 this year. Everyone wearing masks. I was wiping everything down with hand sanitizer, before and after I touched it.... But you know what. I don't remember smelling bad breath, mints, farts, etc... on an airplane. (Of course ten years ago why I have even noticed? I can however tell you the four times someone coughed near me in Hong Kong after about January 15, about when I started wearing a mask when out and about. There was one drunk woman on a cross country flight. I only noticed her boozy breath when she (repeatedly...) leaned in to tell me something especially important.
Back from Hong Kong, I started to get involved in DIY masks (Even though I already had a good supply of N and P95 masks - that I shared around. I reuse them a lot. Between shopping expeditions I leave them in the sun for at least a week) I asked a friend who sews a lot better than I do to help with the DIY masks, she just blew me off, 'the news says, fabric masks don't work.'  I've been wearing a mask since mid January. Was it April when the CDC started recommending it? As soon as my friend got a more reliable source of information than me she got on board. 
I thought I'd get more looks in stores, but no. One checkout clerk I suggested should use hand sanitizer after she sneezed into her hand and then went back to handling my produce, just glared at me. Two weeks later the whole store was masks only, 6' marks on the floor, sneeze protectors at every check-out. They came up to speed brilliantly. 
And while I'm on a tear. When I was teaching health to middle schoolers I decided to do something about respiratory illnesses that usually run rampant through schools. I brought in 2 liter bottles of Purell, and Clorox wipes. I carefully wiped down every surface kids touch, doors, books, tables, chairs. After that whenever I could I'd wipe down the door handles, desks, chair backs and seat where we grasp them to move 'em. I think I noticed fewer respiratory illnesses. I also began using hand sanitizer if I merely thought about it. If my eyes itch I reach for it. The two a year illnesses I normally got vanished - except one morning I woke up and had the thought, 'gee, I better take it easy, I might be coming down with something....' Instead of going about my business and be hammered by the flu during the day, I called in sick and went back to bed. I felt like a complete flake, not ill at all. But that night I felt the flu headache coming on, uh-oh here it comes.... but the next day I woke up feeling great. I'd beaten the flu. This was almost five years ago. I've since made long trips to Japan, the UK and Hong Kong and didn't get the usual mid-trip respiratory illness. But most of what I did is about surface contact and self-infection, so this at best may be interesting but hardly definitive.