If you're just starting out with NativeScript and you love learning by watching videos, Alex Ziskind just released "Building Cross Platform Native Mobile Applications with NativeScript" on Pluralsight to get you started.
Want to learn how to build native apps easily with free tools? This course introduces web developers to NativeScript, an open source framework for building native iOS and Android apps. First, you'll see the initial installation of NativeScript and configuring the modern open source Node.js-based ecosystem. The app that you will be building is a native mobile app developed for a fictitious company, RPS, to help its conference attendees view the conference schedule and create their own agendas. You will be guided through the app development process by seeing reasons behind each choice made to implement a feature, as if the author was an employee of RPS that was tasked with building the conference app. In each module, you'll be introduced to a new concept by implementing an app feature. By the end of this course, you'll be better prepared to tackle a full implementation of a real native app using freely available tooling.
Building Cross Platform Native Mobile Applications with NativeScript