Prevent auto-play (Firefox 26.0)

[MinorEdit]

I am having a couple of issues with this feature since the past week or so.

Whilst there have been a number of instances of this feature failing to function when visiting a video page, the main problem seems to be on channels, where on following a link on youtube to a different channel, the embedded video will play.

Refreshing the page on the channel will prevent the auto-play as desired but has an unusual side-effect. If I do this and then go to watch a video, the channel's embedded video will display in its entirety instead of the page's actual video. So you get an entirely different video to the expected one.