With FAST channels and live sports streaming rising in popularity and top streamers like Netflix, Disney Plus, and Max introducing ad-supported subscriptions, ads are a major part of our current media ecosystem. However, these dynamically inserted ads — which often come from a different origin server or video provider than the main content — frequently encounter performance issues, losing ad impressions and crashing streams. In this session, we will discuss the challenges of Dynamic Ad Insertion, identify its common errors, and demonstrate how to verify them through the unique approach of player-side monitoring.