I don’t know what your setup is and exactly why you want a “kill all” or “stop all” button. I am guessing that you have more than one vimeo embed in different scenes? and when you traverse to a new scene the video continues to play? These are assumptions and I cannot give you a definitive answer based on the information you’ve supplied.
I can confirm what Jonathan is saying about the fact you are getting the elements by Tag name and not Class so that’s one reason why it’s not working and also you mention vimeo videos and again as Jonathan has stated the methods (I posted) above deals with ordinary embedded videos using a “<video>” tag.
Is it possible to upload your document? So we don’t have to guess how you’ve set it up.
Vimeo has it’s own API that you can use to control videos and there may be a better way to control the vimeo embeds in your doc
Here’s a document showing you one way to use the Vimeo API to control embeds in Hype
vimeoAPI.zip (571.8 KB)