Mozilla has finally taken the wraps off of Firefox OS, debuting the operating system in a YouTube video.

Last week saw a leak of Firefox OS Marketplace which gave a us a glimpse into just what to expect from the mobile operating system, but this new video, which has popped up on the Firefox channel, offers up much more in the way of detail.

The demo of the OS is on a unnamed ZTE phone and we get to see what dialling a person looks like, how games will feature on the system and also how the browser and camera will work.

The video has already garnered a number of comments on YouTube, with a few people picking up on the operating system's apparent lag. Given that this is a very early dev build Firefox OS, we don't think there should be a worry about a little bit of stutter.

Mozilla has built Firefox OS on HTML5, which it hopes will bring a lighter OS to the market with faster browsing capabilities and this early look certainly shows this off.

Firefox OS won't be available until 2013, with Brazil the first place to get a phone powered by the operating system.

Both ZTE and Alcatel have confirmed that they will be creating handsets with Firefox OS inside.