1) If you already have your bookmarks bar displayed in Firefox, skip to step 3
2) Click View -> Toolbars -> Bookmarks Toolbar like in the image to the left
3) Drag the red bookmarklet on the very left to your bookmarks bar.
4) When you want to pause and watch later, just click 'PauseForLater' from your bookmarks bar.
5) When you are ready to watch again, just click it again (or visit http://www.pauseforlater.com
from any computer)