Hi mate,
If it is your pop-up blocker you should get a bar across the top of your screen when you try and get a video up, it'll mention pop-up blocker and if you click on it you can change the settings in there.
If it's not that it's probably something in your internet security settings.......way too complicated to explain on here, try clicking Start (bottom left) > Control Panel > Internet Options then have a look in the Security, Privacy + Advanced tabs to see if anything mentions pop-ups or security settings that you can try and change......keep track of what you change though