When I am watching a YouTube video with normal speed I can understand everything with no problem. When I speed up the video to 1.25x my understanding of what someone is saying is a bit worse, but after 1-2 minutes it is very clear again.
I have made an experiment in which I was increasing the video speed gradually to 2x (in ~5 minutes) and I was understanding everything very good. After some time I started the same video again, but then I switched it directly from 1x to 2x and I still could understand what someone is saying in the video, but it was worse than in gradual speed increase.
Why is this happening?