Webcam failing online identification - coursera

Hi,

I am still faily new on Ubuntu but usually get to fix problems myself.
However, I am a bit under pressure on this one:

I take an online course and need to submit assignments with live identification involving my webcam.
Unfortunatelly, the website (coursera) is not able to detect my webcam and the whole online check fails.
My webcam works fine. I have tried to perform the online identification while running Cheese with the camera being on.
The website is still unable to use my camera or to detect whatever it is supposed to detect to make the identification work.

Is there a command line to unblock anything that stops my web browser to respond to their website the way they want?

I would appreciate some help as this is critical for me to be able to identify lproperly on this online course.
Thanks,

Marc