Often when browsing in Firefox, I'll right click on a link, and open it in a separate tab to view later, and go on reading the current page. When the link is a Youtube script, however, playback starts immediately even though the tab isn't active. Other video players (like fora.tv and TED.com) don't start playback until you activate that tab.
Is there a greasemonkey script that I can use to make sure that videos (and especially Youtube videos) are paused unless their tab is active?