fix link

Author: mythz

README.md

@@ -17,7 +17,7 @@ Android (Xamarin) Chat shows integration with ServiceStack server from a Xamarin
     - Getting active event subscribers
 - Add ServiceStack Reference (Chat DTOs)
 
-<img src="https://raw.githubusercontent.com/ServiceStack/Assets/master/img/apps/Chat/demo-preview.png" width="500" href="https://www.youtube.com/watch?v=tImAm2LURu0">
+[![](https://raw.githubusercontent.com/ServiceStack/Assets/master/img/apps/Chat/demo-preview.png)](https://www.youtube.com/watch?v=tImAm2LURu0)
 
 ## Authentication using Xamarin.Auth
 Xamarin.Auth is a component you can use when developing Xamarin clients that authenticate with common OAuth proviers like Twitter, Facebook, etc. This component can also be used with ServiceStack OAuth providers by [creating a wrapper for the `WebAuthenticator`](https://github.com/ServiceStackApps/AndroidXamarinChat/blob/d5d033c49d9b5f73f8679339e05f9dab21ad120f/AndroidXamarinChat/ServiceStackAuthenticator.cs#L10-L64).