Videos don't play

I use Windows 8 and IE 10 and have the latest Flash Player. But videos will not load on a certain site and they advised me to disable "enable hardware acceleration". I followed their instructions but when I right click on the streaming screen I do not get the "Display" box where I can disable hw acceleration. I just get the box to enable or disable access to camera and microphone. Where has the "Display" box gone? I've tried everything I can think of but can't solve this problem and I am getting very frustrated. Can anyone help? Thanks.

Prue