TrueNorth: Thanks again for the advice. Do you have any ideas what it could be?
A blue light could be plenty of things, but if you wanna try to narrow things down further I suppose you could try 'guestimating' it's distance from you and then the shortest distance the object would have had to travel to move out of sight. Divide that distance by the time you were looking for a camera and you have a (very) rough speed with which it would have had to move. Depending on the speed, this might rule out some craft and other airborne objects.
Edited by True North, 29 January 2018 - 01:12 PM.