VCIFBench: Evaluating Complex Instruction Following for Video Understanding

Huangchen Xu, Yuan Wu, Yi Chang


Abstract
Multimodal large language models have made rapid progress in video understanding, yet existing benchmarks largely rely on simple prompts and provide limited evidence about whether models can satisfy explicit output constraints. We introduce VCIFBench, a benchmark for evaluating complex instruction following in video understanding. VCIFBench constructs constraint-rich instructions from both benchmark-adapted and directly video-grounded prompts, covering content, format, style, and structure requirements, and evaluates model outputs with a hybrid verification pipeline. The benchmark contains 306 satisfiable test instructions, 540 DPO training instances, and a 100-item diagnostic set for evaluating whether models can recognize instruction conflicts. Experiments on 10 MLLMs show that joint constraint satisfaction remains challenging. Preference optimization improves instruction following for two model families, while Conflict-100 reveals that models usually execute a satisfiable-looking subset instead of detecting global incompatibility.
Anthology ID:
2026.findings-emnlp.145
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
3034–3064
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.145/
DOI:
Bibkey:
Cite (ACL):
Huangchen Xu, Yuan Wu, and Yi Chang. 2026. VCIFBench: Evaluating Complex Instruction Following for Video Understanding. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 3034–3064, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
VCIFBench: Evaluating Complex Instruction Following for Video Understanding (Xu et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.145.pdf