UX enhancements for a chromeless UI

A functional player still needs clear feedback and convenient interactions. Plan these experiences alongside the core playback controls so viewers always understand the current state and available actions.

Common enhancements include:

1. Loading spinner: Indicate when the player is waiting for video data.
2. Poster: Show an image before initial playback and after the video ends.
3. Up next: Near the end of playback, offer a way to open the next stream and optionally start it automatically.
4. Skip intro: Let viewers skip the current introduction.
5. Ad countdown: Display the remaining duration of the current ad break.
6. Ad markers: Indicate ad-break positions on the scrub bar.

Each enhancement should respond to Player events and state rather than relying on timers or visual state alone. Start with tracking player states, then use the relevant playback and advertising APIs for each interaction.