  Video-grounded dialogue generation (VDG) requires the system to generate a
fluent and accurate answer based on multimodal knowledge. However, the
difficulty in multimodal knowledge utilization brings serious hallucinations to
VDG models in practice. Although previous works mitigate the hallucination in a
variety of ways, they hardly take notice of the importance of the multimodal
knowledge anchor answer tokens. In this paper, we reveal via perplexity that
different VDG models experience varying hallucinations and exhibit diverse
anchor tokens. Based on this observation, we propose M2K-VDG, a model-adaptive
multimodal knowledge anchor enhancement framework for hallucination reduction.
Furthermore, we introduce the counterfactual effect for more accurate anchor
token detection. The experimental results on three popular benchmarks exhibit
the superiority of our approach over state-of-the-art methods, demonstrating
its effectiveness in reducing hallucinations.
