Inaccurate start time in downloaded record

[FilipCZ]

When I download a part of the stream, which was on few days ago, sometimes the start time in downloaded record doesn't correspond to start time specified by me in the CLI argument. Sometimes the downloaded record starts 15-30 minutes before my specified start time, less often the time inaccuracy is in range of hours (and I'm sure this shouldn't have something in common with UTC time used by script). Is this a problem in calculations of the starting segment inside the script or the delay happens on YouTube servers as the days go, so it is hard to fix?

[pkabelka]

I have also observed this, downloading the VoD from same day or the day before is accurate, but it gets worse as the days go back

[IamEld3st]

The difference might be because of the assumption that the segment length is 2 seconds... I don't have a way to get previous segment length because we are using undocumented and unexplored endpoints...
Finding a way to get the full manifest file going back the whole stream duration would be great and more accurate.