Northrup often has pretty good advice. That particular video was disappointing. Yes, there are numerous times when no filter is superior to using one. The cases he made though didn't illustrate the uses of filters when they are most effective. It's as if the all the cases he made were to specifically sell that you shouldn't usually use one. (imagine that...)
A little knowledge about the physics of polarization can go a long way towards getting the best use of one.
- There is no direct substitute in post processing because our consumer cameras don't record raw polarization data, only illuminance.
- The strongest sky darkening always occurs when your shooting axis is at 90 degrees from the sun. (or whatever the illumination is if it's at night.) Shooting near 0 or 180 from the sun especially is often unproductive.. but not always because sometimes bounced light needs to be modified.
- Unless you're intentionally creating an uneven effect, don't exceed 45 or so degree angle of view as you will be unable uniformly apply to all areas in frame.
- Particulate haze and smoke
can respond to polarizers in some circumstances, but it depends on the size of the particulates.
- Glare reduction and sky darkening are not the only uses of a polarizer. Tony fails to mention that a polarizer can also positively
accentuate reflections and illumination when desired for creative use. - Including eyes.
- Some materials (pearlescents, fine grained sparkles) can respond superbly to polarizers because the nature of the shimmer is from reflecting light from many angles. You can shape the nature of the glimmer.
- I've used DXO Clearview a quite lot, It can be useful, but lacks the nuance possible with a polarizer. I have sometimes use both in the same image because they accomplish things differently.
- Utterly indispensable when you want to blacken a lit LCD screen near your subject. Has saved me from extensive post editing on several corporate gigs, not to mention easier metering.
- Nothing makes a rainbow pop like a polarizer because the internal reflections within the raindrops are different polarization than the surface reflections (but wide angle of view may be a limiting factor.)