This thesis investigates the impact of increased value capture by a dominant platform sponsor on user behavior and platform ecosystem stability, focusing on YouTube in a single case experiment. This research aims to address the existing gap in understanding how users respond to this increase in ecosystems characterized by high switching costs. The literature review identified key concepts to build a theoretical framework. The experiment tested the direct effects of increased ad load on 79 participants by simulating a real-world YouTube experience and evaluating behavioral responses. The findings revealed that a higher ad load significantly increased user disengagement. However, the introduction of a premium subscription mitigated these effects to some extent, serving as a stabilizing mechanism. Notably, users willing to pay for premium exhibited aversion to ads independent of increased ad load. This study highlights the trade-offs platforms face between value capture and ecosystem sustainability. While ad monetization can drive short-term profits, excessive strategies risk destabilizing the ecosystem. Practical implications suggest sponsors must balance value capture with reinvestment strategies, focusing on user-centric improvements to maintain ecosystem health. Policymakers are urged to consider regulatory measures ensuring transparency and long-term user welfare in platform governance. The theoretical framework presented in this thesis can serve as a basis for future research in this field of platform research.