I have no idea what it is,
but it behaves like an out of focus star image. The strobe like behavior is on the same time scale as scintillation, or twinkling. I have no idea what the conditions, equipment, or geometry of the sighting was, but if I had to guess, I would say it was a star or reflection, perhaps even a glint off a raindrop on the lens..
Of course, the questions that should have been asked, how long was it visible, did it move, etc, never came up, so it is impossible to make any judgements.