Installed Yosemite. QT Has Question Mark When I launch An Inbedded Video

iMac - recently installed Yosemite

I have videos embedded on the site Actors Access. I always use Safari. All the videos except the latest one that was upload through Actors Access work fine. The last one uploaded when previewed launches the box with Q and the question mark inside. Is this problem with the people who uploaded it? Is this a Safari issue?The video in question works fine on other Macs I own, including another iMax. But they are running on Mavericks.. Works fine on Firefox on my iMac with Yosemite. If 4 videos work on the Actors Access using Safari with Yosemite installed why does this particular video launch the QT Question mark. How do I fix i? And I thank you for any answer.