Since v0.8.4 libv4l decodes JPEG and MJPEG picture formats via libjpeg
instead of using the its own tinyjpeg decoder. For cameras delivering
a non-standars stream this leads to non working or flickering video.

An indication might be the following output on stderr:
"libv4l2: error converting / decoding frame data"

libv4l already takes care of some broken cameras by falling back to
the tinyjpeg decoder. To test if this might help with your camera,
please set the following environment variable before starting the
webcam application:

export LIBV4LCONTROL_FLAGS=32

If this helps please file a bug report caintaing the output of 'lsusb'.