Update README.md

README.md

@@ -22,4 +22,4 @@ It takes the agent 1-2 hours of trial and error to learn to avoid red spheres an
 
 **Website:** [https://ai-creature.github.io](https://ai-creature.github.io)
 
-**Demo Video**: [https://www.youtube.com/watch?v=y1GWcVLL-Xw](https://www.youtube.com/watch?v=y1GWcVLL-Xw)
+**Demo Video:** [![Demo Video](http://img.youtube.com/vi/y1GWcVLL-Xw/0.jpg)](https://www.youtube.com/watch?v=y1GWcVLL-Xw "Demo Video")