Update Intro Video Link (#2637)

Author: mikaelm12

README.md

@@ -7,7 +7,7 @@ Travis:   [![Travis](https://travis-ci.org/aspnet/SignalR.svg?branch=dev)](https
 
 ASP.NET Core SignalR is a new library for ASP.NET Core developers that makes it incredibly simple to add real-time web functionality to your applications. What is "real-time web" functionality? It's the ability to have your server-side code push content to the connected clients as it happens, in real-time.
 
-You can watch an introductory presentation here - [ASP.NET Core SignalR: Build 2018](https://www.youtube.com/watch?v=u0_vkWYYXRc)
+You can watch an introductory presentation here - [ASP.NET Core SignalR: Build 2018](https://www.youtube.com/watch?v=Lws0zOaseIM)
 
 This project is part of ASP.NET Core. You can find samples, documentation and getting started instructions for ASP.NET Core at the [Home](https://github.com/aspnet/home) repo.