Make long videos

Facebook prioritizes videos on 3 basis:
Loyalty and intent: videos that people search for and return to
Video length and view duration: videos that people watch past the 1-minute mark, and that are longer than 3 minutes
Originality: videos that aren’t repurposed from other sources and that have plenty of added value.

As per Facebook, watch time and completion rate are both crucial ranking signals for video because the longer you keep people interested, the higher your video post will be scored by the algorithm, and the higher up in the Facebook newsfeed it will appear.