... I had figured this out on my own long before seeing the video below. It's simple fluid mechanics.
When they tell you to "follow the science," what they're really saying is, "follow what I tell you."
Science isn't obedience.
You can perform your own, simple experiment to validate what that video demonstrates. Put on your mask and take a deep breath, then exhale. You can feel the wind of your exhalation go past your skin. For me, I feel it mostly on my eyes as the air, which is a fluid, flows out through the gaps around my nose. Of course it does. Those gaps are the easiest way to relieve the pressure inside the mask as you exhale.
I've started going back to the gym and lifting weights. Everyone there is wearing a mask, but loosely so we can breathe heavily as we work out. That means they aren't doing a blasted thing. It's all a charade.
Why didn't I realize this before? I had my own experimental data and saw that the people telling me to "follow the science" were closing hiking trails, where it was practically impossible to contract the Wuhan Flu. I had objective data and the "experts" were clearly charlatans.
It just goes to show how easy it is to get sucked into the popular zeitgeist.