In our educational videos there's a preview of the app on the right hand side of the screen. This isn't a secret setting or a feature. This is actually just one of our test iPhone 5s', tethered to our computer. Using iOS 8 and OSX Yosemite, we're recording the phone's screen using Quicktime.
All of your Pixate prototypes will run natively on your device, allowing you to preview them live.
Start off getting either the iOS or Android app or by clicking on "Apps" at the top of Pixate. Once you grab the app, login with your Pixate username and password and you'll see all the Projects and Prototypes you've created in the editor.
Select the Project and Prototype you're currently working on, and the app on your mobile device will automatically update with whatever changes you make in the editor.