It depends on the speaker. Some of them talk so slowly, they are not even bearable at 2x speed, while some others are perfectly fine on 1x.

Depends on the speaker's rate of unfamiliar information density.

The more information they present orally per unit time, and the less I am unfamiliar with the info, the slower they need to go. Better pictures / animation massively boosts my rate of information uptake.

E.g., PBS Spacetime. The host is an efficient communicator and talks at a moderate rate but the topic is usually some super freaky physics stuff. And the diagrams are ok but not amazing. So I find myself playing 1x and pausing often as my brain melts.

The Minute Physics guy is usually efficient, a bit fast, but the illustrations are great. So if the topic isn't blowing my mind too much, 1x no sweat.

Some folks are less efficient and use a lot of words to say hardly anything. Some talk slowly, stumble, even pause a lot. Those I run at 1.5x or even 2x (especially if inefficient and slow) or else it drives me nuts with impatience.

Lol sometimes I go to switch a video to 2x speed only to find that the video was already, in fact, at 2x speed and my ADD gremlin brain truly desires 4x speed. Some people just talk too slow to pad out video length I think

When I found the video playback speed controller extension for my browser, it vastly increased the amount of video I could consume.

There is a downside to it though, once you reach the point where you are watching video at 3x speed, you have to remind yourself to take frequent breaks.

Otherwise, your brain clock will synchronize with the 3x speed and after a few hours of being exposed to that the rest of existence will feel unbearably slow for quite a long time.

Ask me how I know this.

I'll be glad to explain to you in detail the sensation of lifting my arm to close a video and feeling like it took a solid minute for my hand to move from my arm rest to the mouth to click the button.

How it felt to drive home from work once I had synced up and doing 65 mph on the freeway and feeling like I barely had the vehicle in idle.

That shit is great for absorbing a lot of information but actual fucking body horror to experience outside of that narrow use case

I'm over 40 and slowing down with age, so I do 1.3 for most podcasts. I usually leave video at 1X but I'm generally doing something else at the same time like folding laundry or gaming.

Honestly, getting old sucks. Like, I used to play Lemmings a lot and hum the theme song to myself constantly. But I hadn't played the game in 20 years. I heard the song recently, and the tempo sounded twice as fast as I remembered, so much that I fired up emulators and whatnot to confirm... yes, that's really how fast the song is.

The song didn't get faster, I got slower.

For a while I was good up to about 1.6x but after a while Ive been able to push up to 1.75. The advice a blind buddy of mine said is it's a lot like reading or doing anything at speed, at first you have a pretty low max limit but as you go it gets better. You will eventually hit a true max but working up to it its how I can listen at almost 2.5x now.

I can't retain much information if speech is too slow. I usually speed up to 1.5x or 2x but occasionally there are fast talkers who I can stand at 1.25x or even 1x

I've noticed YouTubers pander to this. Listen to a Mark Rober video and you'll notice the voice is chopped so that there is no silence between sentences.

Most of the big names do it.

Depends on the video, but if it's for learning, like a tutorial on how to use a piece of software, I'll usually have to speed it up or I can't focus on it.

Yes

There's nothing I choose to watch or listen to that I would feel the need to speed up playback. If I have to speed it up to be bearable, I'll just turn it off.