Hi,
For creating tutorials you can use Camtasia 7 for screen recording, then Microsoft Movie Maker, Camtasia or Adobe Premiere for Video Editing. You can Google for some tutorials on how to create these tutorials and how to publish them on various media networks such as YouTube.
To create a demo server,
1. Simply create a demo subfolder in your website and install your demo there so you can access the demo by this link http://www.my-site.com/demo
2. Create a demo subdomain and install your demo website in this folder, and will be accessed via this link demo.my-site.com
Both demo will be like any other joomla installation, except it has your content database and extensions setup.
Regards,
Danny