If it is just one person, this could work. Use desktop sharing through messenger. I am not sure if multiple people could see. Now I don't know for sure cause my firewall has my network locked down pretty good and it has never worked for me.

But potentially if you just want to show the user you could do a remote support request and work it that way. Then the user can watch while you operate. Keep in mind that this is not what it was designed for and may not fully work the way you want it to, test before your demo.