Update README.md

Author: ericelliott

README.md

@@ -35,6 +35,7 @@ Some of these links are affiliate links, meaning that if you make a purchase, I
 
 ## Required Viewing
 * [Classical Inheritance is Obsolete: How to Think in Prototypal OO](https://vimeo.com/69255635) by [Eric Elliott](https://twitter.com/_ericelliott) #talk
+* [Composition Over Inheritance](https://www.youtube.com/watch?v=wfMtDGfHWpA) by Mattias Petter Johansson #video
 * [Everything You Never Wanted to Know About JavaScript Numbers](https://www.youtube.com/watch?v=MqHDDtVYJRI) by Bartek Szopka #talk
 * [Asynchronous Programming at Netflix](https://www.youtube.com/watch?v=gawmdhCNy-A) [Jafar Husain](https://twitter.com/jhusain) #talk
 * [What is Reactive Programming?](https://www.youtube.com/watch?v=dwP1TNXE6fc) [Jafar Husain](https://twitter.com/jhusain) explains reactive programming #talk