Almost every time I use YouTube in fullscreen it freezes and doesn't let me back to the desktop.
I want to know if it's possible close to it through the terminal or something like that. Something easier then reboot the PC all the time.
If you can open the terminal :
or change Firefox , if you are using another browser .
you see what happens is that adobe flash did not really freeze it's just that your ubuntu locked itselft. What you have to try is to make sure that your ubuntu does not lock when it's inactive OR whenever it locks go to terminal through ctrl+alt+f1 and type in killall[space][browser] e.g killall chrome.