Details on how to use demofiles, record, video

I would like to be able to record my agents gameplay and save it as a video.

It would be useful to have a little bit more documentation on how to use these flags. From the python side, its unclear how the --demofiles, --record, --video, and --demo flags exposed in the random agent are used, though I can infer some through` dmlab_recording.c`.

I'm currently running the following commands:

`bazel run :python_random_agent -- --video=NameOfAgent --demofiles="/mnt/hgfs/ryanprinster/lab/demofiles"`

`bazel run :python_random_agent -- --record=NameOfAgent --demofiles="/mnt/hgfs/ryanprinster/lab/demofiles"`

Neither seem to do anything except create a `videos/NameOfAgent` and `demos/NameOfAgent` directories in the lab directory. After the second I get the following error after the completion of the agent training:

```ERROR: Moving demo file failed: No such file or directory /tmp/dmlab_temp_folder_PqqR4U/baselab/demos/NameOfAgent/00001.dm_71 /mnt/hgfs/ryanprinster/lab/demofiles/./demos/NameOfAgent/00001.dm_71```.

Note, I'm using a shared file folders on a vm, which is the reason for the weird mnt paths.

Why might I be getting these issues?