Whenever we open any web page having flash video then it automatically starts uploading. Flashblock is an add on browser app which blocks flash and gives you an option for not blocking in case you want to see it. Now its not that you have to click every time if you want to run any flash content. Its a smart app and gives you an option to let show you flash for some particular website. You can always edit it. Also it can detect the embedded flash videos and then accordingly take action. For example if you intend to watch any Youtube video embedded on any other website and you have enabled flash viewing for Youtube then it will not block any Youtube video across the web.
You can get this add on here.