Youtube Embed

Hi
I wonder if anyone can help. I have searched through the forum but not quite sure what the answer is.
I have a multisite school site. I have quite a few teachers contributing to their pages. They are trying to insert a youtube video to let pupils see tutorials etc. The video shows ok when you are logged into the site but not when logged out. I have tried changing from various templates themes etc but to no avail. The insertion has to be easy for the teachers to do but so far no luck. The videos are ok in pages but not in posts. Please could someone enlighten me. Thanks a million.
Usin suffusion as department themes.