Training-Free Sparse Attention for Fast Video Generation via Offline Layer-Wise Sparsity Profiling and Online Bidirectional Co-Clustering. - Jiayi Luo; Jiayu Chen; Jiankun Wang 015; Cong Wang 018; Hanxin Zhu; Qingyun Sun; Chen Gao 001; Zhibo Chen 001; Jianxin Li (CoRR, 2026)