Hi larnoldc, Thank you for your question. In order to turn off autoplay:

In order to change your Firefox Configuration please do the following steps :

1. In the Location bar, type about:config and press Enter. The about:config "This might void your warranty!" warning page may appear.
2. Click I'll be careful, I promise! to continue to the about:config page.
3. Search for media.autoplay.enabled and toggle that preference to false.

Restart Firefox and refresh the webpage with the video. I hope this helps, please post back to help other users :-)

Is there a Flash player used or a HTML5 media player?

You usually get the Flash context menu if you click the Flash player and an HTML5 payer context menu or a normal context menu if you right-click an HTML5 media player.

Are you using an extension to block Flash content?

Thanks. the toggle to false helped, but the videos continue to play after the first selection automatically. i would like to select the videos. i have the Flash player and not using an extension to block flash content.

Flash block {web link} Never be annoyed by a Flash animation again! Blocks Flash so it won't get in your way, but if you want to see it, just click on it

Here's the offending news story URL:

http://www.nbcnews.com/news/us-news/fix-society-transgender-teen-leelah-alcorn-posted-plea-suicide-n277666

My Flash Block add-on stopped it from playing. Give it a try.

I see Flash Block 4.20.13 and Flashblock 1.5.18

https://addons.mozilla.org/en-US/firefox/addon/flashblock/

This is the one I am using. 1.5.18 I don't know the other one.