The video is on a YouTube channel that I haven't looked at carefully but I've seen a few things on it that were pretty good so I was hopeful that this would be as well. The Whiz Bang I referred to in the title of this post is Schlieren photography. In this case made even more Whiz Bang by being slow motion video. There were really slow-mo videos of the air flow caused by talking, breathing, or coughing both with and without a mask. There is an obvious difference made by the mask, a very large reduction in the patterns made visible by the Schlieren setup. The video states that this will allow us to see "if masks really do help to stop the spread of coronavirus". But that is simply untrue. Schlieren photography allows us to see tiny variations in the index of refraction of air usually caused by turbulence. It does NOT allow us to see particles or aerosols which is what would be needed to support the claim I quoted. There is even an image in the video that shows the Schlieren patterns formed in front of different kinds of face coverings. The one with the most obvious patterns is an N95 mask. By the "logic" of this video that would mean that the N95 is the least effective at preventing viral spread and that is simply untrue.
The segment of the video about the Schlieren setup was followed by a longer section that covered lots of ground about how masks work, how the virus spreads, and how those things interact so that masks help stop the spread. There were LOTS of assertions made and they ranged from clearly correct to absurdly wrong. I'm not going to go into any detail on this for several reasons. First, there are simply too many for me to handle in any useful way. Second, I'm not an expert in many of the fields that were covered by these assertions so although I'm pretty sure they are wrong I can't back that up without more time than each assertion is worth.
The segment of the video about the Schlieren setup was followed by a longer section that covered lots of ground about how masks work, how the virus spreads, and how those things interact so that masks help stop the spread. There were LOTS of assertions made and they ranged from clearly correct to absurdly wrong. I'm not going to go into any detail on this for several reasons. First, there are simply too many for me to handle in any useful way. Second, I'm not an expert in many of the fields that were covered by these assertions so although I'm pretty sure they are wrong I can't back that up without more time than each assertion is worth.
The visual impact of the Schlieren imaging and the emotional appeal of that example of "Whiz Bang" will make the misinformation more likely to lodge in the minds of viewers.
