One thing to note is that you are not required to know anything mentioned in this slide to create a website or a web application, or even an Open Web Application; Gaia, or Firefox OS, should be just another browser for you. Only if you want to help out the roll out of Firefox OS v1, or hack the shell to design your own phone, you would need to know how Gaia works. To test your app on a simulated phone, check out r2d2b2g.
Having OS shells and application platforms engineered entirely with web technologies bring tremendous opportunities to the web developers. Web is already a dynamic visual playground — with layouts being invented everyday, from infinite scroll to Mansonry; imaging when these potential being unleashed to the web — Firefox OS is the platform doing that. Join us.