Reasoning is All You Need for Video Generalization: A Counterfactual Benchmark with Sub-question Evaluation

Counterfactual reasoning is crucial for robust video understanding but remains underexplored in existing multimodal benchmarks.In this paper, we introduce COVER (COunterfactual VidEo Reasoning), a multidimensional multimodal benchmark that systematically evaluates MLLMs across the abstract-concrete and perception-cognition dimensions.Beyond prior multimodal benchmarks, COVER decomposes complex queries into structured sub-questions, enabling fine-grained reasoning analysis.Experiments on commercial and open-source models reveal a strong correlation between subquestion accuracy and counterfactual reasoning performance, highlighting the role of structured inference in video understanding.Furthermore, our results suggest a key insight: enhancing the reasoning capability of models is essential for improving the robustness of video understanding.COVER establishes a new standard for assessing MLLMs' logical reasoning abilities in dynamic environments.Our work is available at https://github.com/gongyifan-hash/COVER-Benchmark.