Paper:
Predicting the emotional impact of videos using machine learning is a challenging task. Feature extraction, multi-modal fusion and temporal context fusion are crucial stages for predicting valence and arousal values in the emotional impact, but have not been successfully exploited. In this paper, we proposed a comprehensive framework with innovative designs of model structure and multi-modal fusion strategy. We select the most suitable modalities for valence and arousal tasks respectively and each modal feature is extracted using the modality-specific pretrained deep model on large generic dataset. Two-time-scale structures, one for the intra-clip and the other for the inter-clip, are proposed to capture the temporal dependency of video content and emotional states. To combine the complementary information from multiple modalities, an effective and efficient residual-based progressive training strategy is proposed. Each modality is step-wisely combined into the multi-modal model, responsible for completing the missing parts of features. With all those above, our proposed prediction framework achieves better performance with a large margin compared to the state-of-the-art.

Review:
This paper tackles the problem of affective impact prediction from multimodal sequences. The authors achieve state-of-the-art performance by using (i) a two-time-scale temporal feature extractor, (ii) progressive training strategy for multi-modal feature fusion, and (iii) pretraining. They divide a long video sequence evenly into several clips. The idea of applying one LSTM for intra-clips (short-time) temporal feature extraction and another LSTM for inter-clips (long-time) temporal feature extraction, resulting in two-time-scale, looks reasonable choice but not novel. The proposed progressive training strategy is mainly used for the modality-specific LSTMs training, which is used during the intra-clip short-time modeling phrase. It seems working well in practice. However, from the explanation, it's not clear why this strategy is good for the *complementary* fusion. Each modality LSTM is trained sequentially with features extracted from other fixed modality LSTMs. Also, the authors seem not explaining why they set the training order for LSTMs at this stage to be the descending order of their performance in the previous stage. In the experiments section, two weak baseline models and several previous state-of-the-art models are compared. However, enough ablation studies on the two-time-scale structure and proposed training strategy are not provided to demonstrate that the proposed method does provide complementary multi-modal feature fusion, which is claimed as a contribution. 
Overall, although it achieves state-of-the-art performance on the task, none of the claimed contributions is novel or significant enough. It is a combination of existing ideas (but giving good performance). The proposed training procedure is also weak to be considered as a scientific contribution.