There are 3 options for Player Size under the Player Customisation. Each will define size of the player i.e video on embeded page as follows:
- Responsive player will stretch within parent element (width & height);
- Responsive (fluid) player will stretch width to parent element but will maintain height aspect ratio.
- Fixed player will be in defined size (width & height)
You can test and try different sizes to find the one that best suits your needs.