After recording the video, mujoco told me that the video file has already saved into "/tmp/video_0000000.mp4" The OS I use is Windows, so where can I find the video file and thanks a lot! Moreover, there was error when I press the key "V" the second time to turn off the video recorder. It might be the error resulted from mujoco-py. Code: RuntimeError: An attempt has been made to start a new process before the current process has finished its bootstrapping phase. This probably means that you are not using fork to start your child processes and you have forgotten to use the proper idiom in the main module: if __name__ == '__main__': freeze_support() ... The "freeze_support()" line can be omitted if the program is not going to be frozen to produce an executable.