update README

Author: bySabi

README.md

@@ -6,7 +6,7 @@
 > A React component for scroll to `#hash` links with smooth animations. Scrollchor is a mix of `Scroll` and `Anchor`, a joke name for a useful component.
 
 See it in action:
-* demo [video](https://github.com/bySabi/react-scrollchor/blob/example/demo/scrollchor.mp4?raw=true)
+* demo [video](https://github.com/bySabi/react-scrollchor/blob/example/demo/scrollchor.webm?raw=true)
 * example [page](https://bySabi.github.com/react-scrollchor/) and [source code](https://github.com/bySabi/react-scrollchor/tree/example)