Subtitles: click 
on the player's toolbar to select your preferred language, then click away from the list to close it. Subtitles will appear when you click Play 
.
Chapters: click to quickly navigate to a particular chapter in the video.
Further Reading
For more information please refer to these articles:
Device Overview and Vector Devices
Dock Overview and Vector Docks
Receiver Overview and Vector Receiver
Cloud Dashboards, Cloud Widgets and Reports