[doc] Update README

README.md

@@ -33,6 +33,14 @@ See [here][GitHub releases] for earlier releases.
 
 Note that Tempel is [not intended](../../wiki/3-Faq#can-i-decrypt-tempel-data-with-other-tools) for interop with other cryptographic tools/APIs.
 
+## Video demo
+
+See for  intro and usage:
+
+<a href="https://www.youtube.com/watch?v=sULZVFhR848" target="_blank">
+ <img src="https://img.youtube.com/vi/sULZVFhR848/maxresdefault.jpg" alt="Tempel demo video" width="640" border="0" />
+</a>
+
 ## Roadmap
 
 Tempel has a **fixed scope**, and is **fully complete**. I'm happy with its design and implementation, and believe it meets all its objectives in its current form. I'm not anticipating significant changes.