Visual Studio Code or VS Code is a completely free, light weight, cross platform, multi-language code editor, allowing you to write code across Linux, OS X and of course, Windows. Its important to note that while VS Code lets you edit code it is not an IDE and shouldn't be confused as a stripped down version of Visual Studio Community or Express editions. Where VS Code excels is in those times when you don't really need all the "extra" features that an IDE brings to the table. Like in the video example where it is used to edit scripts for the Unity game engine. With support for multiple languages (more being added still) it is also a great fit as a general editor for everything from console apps to cloud apps and all those in between. I highly recommend taking a look at it for your next coding adventure.
Visual Studio Code Download - https://code.visualstudio.com/
Unity for Linux Download - http://bit.ly/1QYpiro