I established an audio call with a friend and then tried to send him the video from my webcam (which was properly displayed in my preview). Empathy noticed the video stream on his side as the call window was enlarged but nothing was displayed.
SE log from my side (send video): http://people.collabora.co.uk/~cassidy/logs/se-send-yasha-video.log
SE log from his side (receive video) http://people.collabora.co.uk/~cassidy/logs/se-yasha-receive-video.log
We were both using Empathy 2.23.6, telepathy-stream-engine 0.5.3, telepathy-gabble 0.7.7, libjingle 0.3.11, Farsight 0.1.25 and gstreamer-plugins-farsight 0.12.9.