Yeah, sure. And you can add arbitrary anchors to a a video stream that you're converting. Not just a point in the movie, but a face on the screen at the point in a movie. Like, if someone is giving a Powerpoint presentation and presents a chart, you could highlight a bar in that chart and add some text, or cause the video to pause and add an explanatory slide.

Segments are usually fixed byte size or duration to optimize for storage and delivery, anchors/chapters are not. They need to be defined separately.