Browser: Chrome 21.0.1155.2

I wrote a simple demo to test getUserMedia() function. The demo is just to show the video stream from my local camera.

But I encountered a strange problem: 

1) If I open the test.html directly in the browser(double click or drag to the browser), there will be a popup window to obtain user's confirmation. I clicked the "Allowed" button, but I could see nothing on the page. At the same time, however, there was a success notification on the taskbar, saying "file:// is using your camera and microphone". 

2) If I put the test.html to apache's home directory and open the page through "http://localhost/test.html", there will also be a popup window. When I clicked the "Allowed" button, I could see the video stream from my camera successfully! At the same time, there was also a success notification on the taskbar, saying "http://localhost is using your camera and microphone".

I was wondering what is the reason of the problem. Is there any difference between "double-click open" and "localhost open" when calling getUserMedia() function?

Thanks.