Most Flash requires JavaScript being turned on as that is how the media code is delivered. Check it out using YouTube with JavaScript turned off.
I use Firefox with the add-on called
NoScript. Many times when it says I need Flash player to play, it is because I have to allow JavaScript temporarily for the site. Never looked for anything like this for IE. You would have to go through the long steps of turning on/off scripting in IE. Maybe IE has a web developer plug-in that allows more control.
For sites that do not deliver the media code via JavaScript, turning JS off will not work. I see the answer given you
here is to "Right click the flash object and uncheck Play".