The AI video model HappyHorse-1.0 has unexpectedly topped the AI Video Arena rankings on Artificial Analysis, surpassing Seedance 2.0. This text-to-video model, which emerged without any formal launch or corporate backing, achieved a higher Elo score based on real user blind tests, outperforming mainstream competitors like KeLing and Tiangong. The model's success has sparked widespread speculation about its origins, with many suggesting it is an optimized version of the open-source daVinci-MagiHuman model developed by Sand.ai and the Generative Artificial Intelligence Research Lab in China. HappyHorse-1.0's rapid rise has raised questions about its ability to outperform established models in just two weeks. Analysts suggest that its success may be due to specific optimizations for evaluation scenarios, particularly in portrait generation, which accounts for a significant portion of the blind test samples. While the model's performance in complex scenarios remains debated, its achievement signals a potential shift in the AI video generation landscape, challenging the dominance of proprietary models and highlighting the growing capabilities of open-source alternatives.