Thanks for your reply, Joe.
So it seems not everybody is affected by the issue. Which also explains why it is still not well-known, and fixed!
I have tested different videos, random videos from VMWare, Cisco (what I normally watch) and Microsoft, and all show the same issue. As soon as I enabled fast playback the videos stop after some time.
I am not sure if the "skip 10 seconds back" is the issue or just the poor performance from the streaming platform.
I am located in Eastern Europe and I have the issue for quite some time, with different laptops, browsers, times, and so on.
I have tried different places, with quite good bandwidth and never had any issues with normal playback!
I do NOT want to rule out that some of the ISPs are limiting the speed ;-) but someone should take a look, if there is a general issue with video playback for certain regions (streaming platform?).
Most of the last year (and before) it was fine and at one point my issues started. And it is quite irritating. I am so much used to watch the videos in fast playback.