Excellent presentation and explanation. I agree with ~90% of it except the small part at 4m54s where he tries to give an answer about the existence of noise. Yes, sensor readout noise and A/D quantization noise exist, but he forgot the big elephant in the room: photon shot noise ( https://en.wikipedia.org/wiki/Shot_noise ). Light is inherently quantum mechanical, and the lower the brightness of a scene, the more that the discrete nature of light shows up in captured images.

Lately I've been researching cameras for astronomy, especially for deep-sky objects (DSOs) like nebulae that require hours of exposure time. The marketing material for these cameras go into a lot of detail: quantum efficiency (the percent chance that a photon converts into an electron), dark noise at different temperatures (fractions of electrons per second), readout noise (usually around 1 electron), and well depth (usually around 10k electrons). Compared to general photography, the astro community much more motivated to explain and keep track of all the sources of noise. Random product example: https://www.zwoastro.com/product/asi585mc-mm-pro/

That's a pretty good demo!

Very limited camera choices, though.

Yeah, it would be interesting and useful to see this across many more cameras.

dpreview is good for that. They shoot a test image of every camera on the market, and you can compare specific iso values on the same subject side by side.

Some of the new Nikon cameras have excellent high-ISO performance. Also, they now own RED, so we should see some interesting stuff, down the road.