@qber Nah, what the command does is take the video4linux2 source /dev/video0, encode it with webm format defaults and output to STDOUT ("-"). Then it pipes that output ("|") to mplayer which reads from STDIN ("-" again).

So you don't need an X connection on the remote server, as what you're getting is the raw webm-formatted video data.
(-C could be usable though, but I doubt you get much better compression as webm has already done all the work ;))