YouTube is the second most popular website in the world. Over 300 hours worthof videos are uploaded every minute and 5 billion videos are watched every day - almost one video per person worldwide. Because videos can deliveracomplex messageinaway that captures the audience's attention more effectively than text-based platforms, it has become one of the most relevant platforms in the age of digital mass communication. This makes the analysis of YouTube content and user behavior invaluable not only to information scientists but also communication researchers, journalists, sociologists, and many more. There exists a number of YouTube analysis tools but few of them provide an in-depth qualitative and quantitative insights into user behavior or networks from massive aggregated data. Towards that direction, we introduce YouTubeTracker - a tool designed to gather YouTube data and gain insights on content and users. This tool can help identify leading actors, networks and spheres of influence, emerging popular trends, as well as user opinion. This analysis can also be used to understand user engagement and social networks. This can help reveal suspicious and inorganic behaviors (e.g., trolling, botting) causing algorithmic manipulations. Utility of the YouTubeTracker application is demonstrated via a case study on NATO's 2018 Trident Juncture Exercise.