Reproducible here
Same ”double free or corruption (!prev)” reproducible here too (VLC 3.0.9.2-1, Ubuntu 20.04), even more easily: the position doesn’t matter, and the first attempt to screenshot is already enough to trigger the issue.
I came across this when trying to screenshot a Superman cartoon I downloaded from Internet Archive [1].
* [1] https://archive.org/download/dom-6746superman-episode7-theundergroundworld512kb/dom-6746superman-episode7-theundergroundworld512kb.mp4