To quote the Google support article (emphasis mine):
If you select Allow on a "http" URL your preference will not be
remembered in future visits. If you select Allow on a "https" URL,
your preference will be remembered in future visits. You can monitor
which site is using your camera and microphone by clicking the camera
icon or microphone icon microphone icon in your Windows system tray or
Mac status menu.
Similarly, one will often see the video camera icon in Chrome's address bar during such requests, or of course the flash-based camera prompts.
So the question I pose is whether you're seeing this on a flash webcam site, or any that would attempt to use the webcam, such as an HTML5 website (a good one to test is here: http://wolframhempel.github.io/photobooth-js/).
If you verify it works with HTML5 and not flash, the culprit may be the flash plugin, or settings on that particular website.