The 2015 devsummit session recordings have started coming online.
Below is a list of .NET Runtime related session recordings - More to come (I'll update the list as they do)
.NET Specific sessions:
Getting Started with the ArcGIS Runtime SDK for .NET | Esri Video
The first steps to using the runtime in a .NET-based app and an overview
ArcGIS Runtime SDK for .NET: Using MVVM | Esri Video
Goes through rewriting an app to use good MVVM patterns
ArcGIS Runtime SDK for .NET: Tips and Tricks | Esri Video
The .NET Team's Top 10 tips - Lots of little good tidbits for you
Preview of ArcGIS Runtime and Xamarin | Esri Video
Get a sneak peak of the runtime for Xamarin
Runtime sessions that apply to all the supported platforms
Getting Started with the ArcGIS Runtime | Esri Video
Intro about the runtimes in general
ArcGIS Runtime SDKs: Building Offline Apps, Part I | Esri Video
ArcGIS Runtime SDKs: Building Offline Apps, Part II | Esri Video
Two-part series on going offline with the runtime
ArcGIS Runtime SDKs: Core Display Architecture Performance Tips and Tricks | Esri Video
Great low-level look at how the Runtime Rendering engine works and how you can optimize your rendering with this knowledge