In order to understand the effects of QoE (Quality of Experience) on User Engagement, we measured QoE metrics on client side during Roland Garros 2013, an international tennis tournament broadcast live over the Internet. We analyze the impacts of four metrics on User Engagement: the video startup time, buffering ratio, average bitrate and content popularity. Our results demonstrate that video buffering is a critical parameter which impacts end-user satisfaction. We show also that content popularity is an important parameter of our analysis, whereas the video startup time is less significant. We highlight the relationship between the average bitrate and User Engagement in the case of popular content. Finally we confirm a correlation between metrics.