Update README.md

README.md

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 Built for the **Build Small Hackathon 2026 — Thousand Token Wood** track.
 
-**Demo video:** https://youtu.be/<will update later> 
+**Demo video:** https://drive.google.com/file/d/1umIJRb_OYZ2gxcbliFNa_YmhGK_y_0ik/view?usp=sharing                                            
 **Social post:** https://x.com/iagained/status/2066384319929778645?s=20  
 **Blog post:** https://huggingface.co/blog/build-small-hackathon/tiny-civilization  
 **Agent traces:** https://huggingface.co/datasets/build-small-hackathon/tiny-civilization-traces