VLC can't convert all movies to the required file format for streaming.
There are a couple of things you can do to get info on what is going wrong. Hopefully this will help you figure out how to avoid the problem or work round it.
(if you figure out something that is generally useful - then please let me know)
Try downloading the mp4 Building on the Past movie
(Right click on the link and click 'save content as...')
I have tested this movie on Windows and Mac to check that VLC Streamer can handle it.
(movie is hosted by the internet archive )
this will run the command that VLC streamer is using to convert the movie. You should see output from VLC in a new window. Hopefully this will give additional information on what is not working.
this contains the output which VLC produced. Hopefully it is helpful.
You can also run the command from the cmd.txt file (copy it into a terminal window) if you want to re-run the command or modify it