Most cameras will stream "raw video" but special media players will be required to view it unless it is first encoded to a format like mpeg, h.264 and wrapped in a container like avi, swf, mp4.
Some cameras have hardware encoders built into the camera and in addition to raw video, can also stream encoded video. The Logitech HD920 has mpeg and h.264 encoders.
Display camera modes
1. Install h.294 library libx264
git clone git://git.videolan.org/x264.git cd x264 ./configure --enable-static --enable-shared make make install ldconfig
2. Install ffmpeg
git clone git://source.ffmpeg.org/ffmpeg.git cd ffmpeg ./configure --enable-gpl --enable-libx264 make make install ldconfig