The audio description one is complicated.
I believe it should be easy to turn on and off. The average no tech person should be able to turn it on and off in browser settings, or tv settings.
For the record - I am deafblind.
I lost a lot of my hearing before dropping to ten degrees of vision.
I struggle to comprehend speech.
So, being around people who are talking takes a day's energy, and few days to recover from.
Watching tv, there times I wish I could turn on description - in the captions.
Even with ten degrees of vision, I still comprehend reading better than spoken.
I tried audio description once, turned it on by accident. After five minutes of a show I knew, I had to turn off the tv, and stay in bed two days to get rid of the headache form all of the conflicting and over riding speech.
It is valuable for people. I just wish there was a way to pause the show speech while listening to (or reading) the audio description that more sighted people may, or may not, get from watching the show.
Definitely one of those tools that should be easy to adjust for those who need it.