Before you replace your webcam, make sure you have a good
network connection, your computer isn't working overtime on another
application and your webcam driver is current.
Older webcams than 2006 may not perform adequately. Audio or
video may work but not both together. If your network connection is
good and your computer is not be over-loaded, then perhaps you
should get a new webcam.
Read Microsoft's recommendations for Lync optimized
Try disconnecting and restarting your video call to see if video
or audio improves.