video chat only possible if both sides can send video
Gajim's video chat feature only works if both sides are able to send a video stream.
I think that it's quite a possible scenario that only one person is able to send a video stream; not because the client does not support it, but because the required webcam is missing.
Gajim should be able to establish a video chat connection with only one side sending a video stream. (e.g. Gajim on both sides, but only one person has a webcam connected)