Click the big play/pause button in the middle of the screen, and use the slider beneath it to jump forward/backward. Don't click the buttons on the individual YouTube players.
This can be due to your internet connection speed. Streaming multiple videos requires a fast connection. Try lowering the video quality in each YouTube player's bottom-right menu.
Send an email to firstname.lastname@example.org!
Increase the video quality in each YouTube player's bottom-right menu. If you are logged into YouTube that will help it save your preference.
We will be adding this capability soon.