Video player with chapter support?
There are only two of them.

SimpleCinema (by DeveloperRevolution): it works with both Quicktime-variant chapters and Nero-variant chapters. The former is more popular. It is a small player that just does one thing.

LVOE Media: If you are not sign language user, you probably will find its sign-language-optimized interface a bit weird, but I've tested that it can do Quicktime variant chapters, Nero-variant I did not test against this player.

Chapters in video files is a good feature, unfortunately most people don't know it exists.