This research aims to enhance the critical thinking skills of 10th-grade students at SMA Negeri 4 Pematangsiantar through the implementation of the Problem-Based Learning (PBL) model, supported by video media. The students' critical thinking is assessed based on their ability to analyze information, distinguish between facts and opinions, and evaluate the reliability of the information they receive, particularly in relation to the influence of mass media. This study uses a Classroom Action Research (CAR) design consisting of two cycles, with each cycle including the stages of planning, implementation, observation, and reflection. The results of the research showed a significant improvement in students' critical thinking from the first cycle to the second. In the first cycle, the average critical thinking score was only 68%, with the main weakness being the evaluation of information reliability. However, after improvements in the second cycle, the average score increased to 90%. Students became more engaged in group discussions, better able to analyze videos, and more critical in evaluating media content. The use of video as a learning medium was also found to be effective in facilitating visual and contextual understanding of the material. The research employed a qualitative method with a descriptive approach. Data collection techniques included observation, interviews, and documentation. The data analysis techniques involved data reduction by selecting raw data into useful information, data presentation in the form of descriptions, graphs, and tables, and drawing conclusions based on the research findings that addressed the research questions. The use of the Problem-Based Learning model, supported by video media, followed the PBL syntax, including steps such as orienting students to the problem, organizing students for learning, guiding individual or group investigations, developing and presenting results, and analyzing and evaluating the problem-solving process. This approach proved effective in enhancing student motivation and independence in critical thinking and responsibility towards the influence of mass media in the 10th-grade class at SMA Negeri 4 Pematangsiantar. In conclusion, the implementation of the PBL model with video media significantly improved students' critical thinking skills. Recommendations include optimizing the use of video, providing more intensive support for students in need, strengthening group discussions, and continuing critical thinking exercises.