Since recently, Bubble has started to enforce the 'opt-in cookie policy' for apps that have the setting on/checked. This means that any embedded video or iframe will also inherit that setting, which has the side-effect of not working with YouTube or Vimeo's cookie policies as they do not allow playback in embedded frames to people that do not allow cookies. If you have this setting turned on, you need to either have a sign in or cookie consent workflow run before you show users embedded videos. Alternatively, you could turn this setting off my default.