To share a webcam in BigBlueButton:
Select the webcam icon from the media bar and follow the join prompts.
If you are using Chrome Browser and receive the message “The webcam is in use by another application” be sure you have allowed the permissions prompted by Chrome.
The permissions will usually appear in the upper right hand corner of the browser:
If you are still receiving the message “The webcam is in use by another application” check that your webcam is not in use by another application such as Skype or Facebook video chat.