I kindly disagree, I only add supports when there is an angle bigger than 60°. It depends on the printer, I tested mine and 60° is the limit.

And about this video, now that I think about it, maybe the octolapse or whatever software that made the video probably touched the piece when it got into place for the screenshot, and made it fall.

Ironically if the video was not taken, the piece may have come ok.