The emergence of UHD video format induces larger screens and involves a wider stimulated viewing angle. Therefore, its effect on visual attention can be questioned since it can impact quality assessment, metrics but also the whole chain of video processing and creation. Moreover, changes in visual attention from different viewing conditions challenge visual attention models. In this paper, we present, first, a comparative study of visual attention and viewing behavior, based on eye tracking data obtained in three different viewing conditions (SD-12°, HD-30° and UHD-60°). Then, we present a new video eye tracking database which permits a dynamic analysis of the impact of viewing immersion on visual attentional process in videos.