somewhat better readme

README.md

@@ -1,6 +1,11 @@
-pagerecorder
-============
+Page Recorder FirefoxDevTools add-on
+====================================
 
-Firefox DevTools extension that records changes on a page:
-- DOM mutations
-- DOM events
+pagerecorder is a really bad name but naming things is hard.
+
+This is a Firefox DevTools add-on that records changes on the current page.
+Start it and it will record DOM mutations and events, plus it will remember the state of the page and the target node for each change.
+
+Stop it and it will list those changes in the toolbox so that you can mouseover them and see what happened in the page while it was being recorded.
+
+Here's a short video: https://www.youtube.com/watch?v=y6JSoddYQKg&feature=youtu.be