If you want a solution, you need to step outside your "normie" box. I have given a
solution of sorts over here:
https://groups.google.com/g/video-downloadhelper-q-and-a/c/w9993gUmxr4
Too many downloads with VDH work fine for anybody to conclude that VDH is causing this
problem. My suspicion is that there is some sort of transient error on the connection
that puts some bad information into the output file. I hit the problem myself today. I
have not yet dealt with it, but I will use what I describe in the thread whose link I
just cited. I have skimmed through the file enough to discover that about the first 1
hour 45 minutes of the file is fine. Then suddenly the video speeds up but the audio
remains correct for the remaining 2 hours of the file. Of course, video being too fast,
it stops before the audio runs out.
So either you roll up your sleeves & learn something new or just throw the damaged video
away & move on to other things.