Update README.md

README.md

 # 🌍 Developing a Basic 3D Web Visualization with CesiumJS and LLM Tools
 
+[Watch the demo video](https://transfer.hft-stuttgart.de/gitlab/ugl/3d-visualization-sample/-/blob/master/demo-3d-vis-cursor.mp4)
+
 This guide shows how to build a simple **3D web application** using **CesiumJS**.  
 The example focuses on visualizing 3D models in **Germany** using open 3D Tiles and terrain data.  
 We also explore how **Large Language Models (LLMs)** can script and accelerate the development process.