In OctoPrint, I have the webcam set to flip horizontally + vertically (to achieve a 180 degree rotation). It looks fine within the OctoPrint interface, but when I go to /webcam/?action=stream the stream reflects the unmodified webcam video (i.e. it's upside down for me)
I prefer to be able to use the full-screen video feed, since the video feed embedded within the OctoPrint interface is so small that it's hard to see when the print of a small part has failed catastrophically.
(on that note, it would be nice if there were an easy way to open the full-sized video feed from directly within OctoPrint...)
I'm using the latest Octoprint on an RPi3 with the official Raspberry Pi cam, which is mounted in an enclosure from thingiverse that happens to mount it upside down.