After a new install of Octoprint 1.4.0 on my SD card, as the old SD stopped working, my Logitec Pro 9000 was not recognized any more. Since the camera worked great in the previous setup without any installation (P&P) I had to modify the octoprint.txt file to set the camera stream to "Auto". I believe that the # in front of the command may be a mistake, since the command was thus completely ignored.
I removed the # using PuTTY and then: sudo nano /boot/octoprint.txt. Hope this is helpful information for people running in the same problem with a new install.
i have been having same problems with same camera with a new setup, i edited octoprint.txt to remove the # sign, but did not solve my problem. 