To record a demo you need to be admin, so -- even on a locally run server -- you will need to set a master-password and authenticate yourself with this to gain admin status. If you're running a linux-machine you could start a (private [i.e. non-public]) server something like this
bin_unix/linux_server -mlocalhost -pMY_SECRET_PASSWORD
and then in your client execute
It is not possible to do this on the mini-server running for your regular client, you will need to run a dedicated server and then connect localhost to it!
This page is just a stub -- please feel free to elaborate more on this subject.