Advances in Generative AI have made video-level deepfake detection increasingly challenging, exposing the limitations of current detection techniques. In this paper, we present HOLA, our solution to the Video-Level Deepfake Detection track of 2025 1M-Deepfakes Detection Challenge. Inspired by the success of large-scale pre-training in the general domain, we first scale audio-visual self-supervised pre-training in the multimodal video-level deepfake detection, which leverages our self-built dataset of 1.81M samples, thereby leading to a unified two-stage framework. To be specific, HOLA features an iterative-aware cross-modal learning module for selective audio-visual interactions, hierarchical contextual modeling with gated aggregations under the local-global perspective, and a pyramid-like refiner for scale-aware cross-grained semantic enhancements. Moreover, we propose the pseudo supervised singal injection strategy to further boost model performance. Extensive experiments across expert models and MLLMs impressivly demonstrate the effectiveness of our proposed HOLA. We also conduct a series of ablation studies to explore the crucial design factors of our introduced components. Remarkably, our HOLA ranks 1st, outperforming the second by 0.0476 AUC on the TestA set.

The continual advancements in Generative Artificial Intelligence have created substantial hurdles for accurate deepfake detection, leading to limitations of currently popular detection methods across content-driven video-level deepfake detection scenarios. In this paper, we present the solutions to the Video-Level Deepfake Detection task. Our empirical findings demonstrate that modeling correlations of audio-visual modalities is important for video-level deepfake detection. Therefore, we introduce the model denoted Audio-Visual Local-Global Neural Network (i.e., AV-LGNN) in which the core design is the proposed AV-LGI Module (Audio-Visual Local-Global Interaction Module). The AV-LGI Module is composed of three stages: Local Intra-Region Interaction, Global Inter-Region Interaction, and Local-Global Interaction, which can better capture detailed information at local-level and efficiently learn the fine-grained correlations of inter-modalities in video deepfake detection under lower computational overheads. We further propose an adaptive modality selection strategy to facilitate model learning. Besides, a variety of data augmentation techniques are incorporated for audio-visual branches to enhance the robustness of the AV-LGNN. The experimental results verify the effectiveness of our model.