Backport to branch(3) : update README (#2522)

Author: feeblefakie

README.md

@@ -1,7 +1,20 @@
-# ScalarDB
+<p align="center">
+  <img src='docs/images/scalardb.png'>
+</p>
 
+---
+
+## What is ScalarDB?
 ScalarDB is a cross-database HTAP engine. It achieves ACID transactions and real-time analytics across diverse databases to simplify the complexity of managing multiple databases.
 
+<p align="center">
+  <a href='https://www.youtube.com/watch?v=lW6nCEJV-gs' target="_blank"><img src='docs/images/scalardb-video-preview.png' width='70%'></a>
+</p>
+
+## Docs
+
+See our [User Documentation](https://scalardb.scalar-labs.com/docs/latest/).
+
 ## Install
 
 The library is available on [maven central repository](https://mvnrepository.com/artifact/com.scalar-labs/scalardb).
@@ -23,10 +36,6 @@ To add a dependency using Maven:
 </dependency>
 ```
 
-## Docs
-
-See our [User Documentation](https://scalardb.scalar-labs.com/docs/latest/).
-
 ## Contributing
 
 This library is mainly maintained by the Scalar Engineering Team, but of course we appreciate any help.