What have you tried so far? Video can be played using either: * built-in HTML video player (for example, on YouTube) * a plugin such as Flash '''''The HTML5 Player''''' Firefox has an internal setting to stop videos from autoplaying. This sometimes leads to the strange appearance of a pause button on a stopped video. In that case, to play the video, click the pause button then click the play button. Here's where you set this feature: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful. (2) In the search box above the list, type or paste '''autop''' and pause while the list is filtered (3) Double-click the '''media.autoplay.enabled''' preference to switch the value from true to false '''''Plugin players''''' Try setting Flash to Click-to-Play ("Ask to Activate"). This will delay Flash from starting on a page until you approve it. Open the Add-ons page using either: * Ctrl+Shift+a * "3-bar" menu button (or Tools menu) > Add-ons In the left column, click Plugins. Look for "Shockwave Flash" and change "Always Activate" to "Ask to Activate". With this setting, when you visit a site that wants to use Flash, you should see a notification icon in the address bar and usually (but not always) one of the following: a link in a black rectangle in the page or an infobar sliding down between the toolbar area and the page. The plugin notification icon in the address bar typically looks like a small, dark gray Lego block. When the page wants to use a blocked plugin, the icon turns red to alert you to the concern. If you see a good reason to use Flash, and the site looks trustworthy, you can go ahead and click the notification icon in the address bar to allow Flash. You can trust the site for the time being or permanently. But some pages use Flash only for tracking or playing ads, so if you don't see an immediate need for Flash, feel free to ignore the notification! It will just sit there in case you want to use it later. ''If you want finer control:'' This extension addresses the issue of only wanting ''some'' videos on a page to play: https://addons.mozilla.org/firefox/addon/click-to-play-per-element/ (I haven't tried it myself)