Send a link to the tutorial you are speaking of.
There is a pause button in the player but sometimes if the height of the video isn’t setup correctly it will cut off the controls.
You might also try ccleaner to clean out your cookies and other pc stuff as the problem could be associated with FF getting confused with the bulk of cookies or something. Good program I use: https://www.ccleaner.com/
I’ve found this is a Cookie issue generally associated with Firefox. I experience this quite a bit when using that browser and decided to switch to Chrome. What browser are you using and what OS?