With this script you can create a video over a rosbag.
rosbag record /camera/image/compressed
Note move the rosbag at same folder which contains rosbag2video.py, then execute the following:
python rosbag2video.py -r 50 -o <nameofvideo>.mp4 <rosbagname>.bag
Example:
python rosbag2video.py -r 50 -o test.mp4 2016-03-07-17-17-02.bag