Here is a note from the BigBlueButton team that was distributed to the Canvas administrators. If you’re using the Conferences tool in Canvas, it might apply to you.
Last week, when Google updated the Chrome browser to version 27, they added a prompt for permission to access the user’s webcam and microphone.
Canvas users will see the prompt appear just below the address line (see screen shot below).
This prompt is in addition to the Flash Security Manager which prompts for access to the webcam and microphone (shown below).
Google indicates that they added their own prompt to Chrome for greater security.
Bottom line: You now need to accept two prompts to grant BigBlueButton access to your webcam and microphone.