The video call quality with gmail users is very poor.
While in gmail <-> gmail calls the image is fluid and defined, in empathy <-> gmail the image is really very pixeled and slow
instead empathy <-> empathy calls are OK.
Does this still occur? If it does, on which OS are you using Empathy, and which GStreamer video codecs do you have?
I suspect it may have been caused by Empathy and gmail not having many video codecs they could choose between: the Google web interface currently only knows about H.263 and H.264, and until recently, Linux distributions didn't generally ship either H.263 or H.264.