I did find a work around by setting the stream label in firefox as "default" and setting stream id as null.
This way the user in a chrome browser can see the firefox video at his end.
But the problem occurs when the chrome user starts his video, then firefox video hangs in both ends.
You might try to write firefox specific codes without stream labels by detecting the browser, so that all your chrome users can use multiple labels of stream, where as the firefox user
will only use single stream with label default.