Seems to work on most YouTube videos--but it will not work on one (http://support-us.samsung.com/spsn/main.jsp) and I don't know how many others. I often have to return to this Samsung page. The only support the developer offers is via Mozilla Discourse--but my inquiry there was rejected with the inscrutable message, "The category you sent this email to only allows replies from users with valid accounts and known email addresses. If you believe this is an error, contact a staff member." The rejection linked to a list of staff members--with *no way* to reach any of them! I have a working account with Mozilla Discourse, and must have a "known email address," as that's where I received the rejection of my inquiry. Very strange indeed.