Sure but that's obviously not how it's used. Also, for the first one which is the one he's actually using I couldn't make out a single word even when reading at the same time.

It's like learning a foreign language. At first, native speakers seem to speak so fast that all words flow into each other without distinction.

As you improve, you begin noticing words you already know, and when someone speaks deliberately slow, you can puzzle together sentences.

Eventually, you can understand speech at a normal conversational speed. Most people probably stop at that level, because they don't need more.

But e.g. when watching recorded lectures, I tend to crank up the speed to 1.5x or even 2x until I need to think more about something. The sped-up speech is mostly still quite understandable.

There is no reason to suppose you can't improve your hearing beyond the limits on humans' ability to form coherent thoughts from scratch and move their mouth in the right pattern. Just keep increasing the speed, attune yourself to the artificial voice and then increase it even more until you're at a level that makes untrained people feel like non-native speakers.