The duration, time, and fullscreen button can be any object that you want. You simply have to assign the right graphic style name to it followed by the name of the table. The graphic style names are
QQ-duration-YourPlayerName
QQ-time-YourPlayerName
QQ-fullscreen-YourPlayerName
The video player graphic style names for the default video player are the following because the name of the default video player is ‘player1’
QQ-duration-player1
QQ-time-player1
QQ-fullscreen-player1.

If you are having trouble setting up your graphic styles then please check out this article. (link to graphic style article)
Customization
Graphic style names are used for the duration, time, and fullscreen button because it offers you a lot more flexibility for customization. You can easily customize these features through the text panel, fill panel, stroke panel, etc. You can even add your image for the fullscreen button.
Important Note: Do not apply letter-spacing to the duration, time, or fullscreen button. This will cause it to not appear properly.