Sometimes a friend will send a cool You tube video within messages on desktop, I'll click play. Then I'll quite messages (on desktop) yet sound video still goes on. Then quit all apps and still going on! Stumped.

Open Applications>Utilities>Activity Monitor and look at what is using your CPU. You may find something unexpected, perhaps running in the background playing the video.

Ira, thanks, ok closed all apps, brought up activity monitor and and think the thing is, it's embedded inside of messages, so only way to turn it off, click on it pauses.. so I think there is no app controlling it.

I guess I did not try just clicking on the video thumbnail, but thats it all embedded.

When you say "I'll quit messages…" do you mean actually quitting (ie. Messages no longer shows up in Activity monitor)?

Thanks Joe, those videos embedded in messages my friend sends me; if just click on it is pauses. I did not see that for some reason, so I was looking for an app to close them.

I think the message engine fully controls them though.