Imagine you're watching a video, but you want to pause it and restart it
later. This free add-on called Pause for Later, allows you to do just that
with the added bonus that you can restart and watch your video from another
computer. This makes it ideal for tutorials where you can start watching at
work or college and finish at home. It's available for most browsers.
http://www.techsupportalert.com/content/pause-youtube-videos-then-watch-them-later-anywhere.htm