YouTube was blocked by government fiat in Turkey a year ago. As I recall Turkey's constitutional court overruled that ban a few months later, but the communications minister was dragging its feet in complying. I lost track of what happened after that, but from what you report it sounds as though it's been blocked again. I can only surmise that will occur repeatedly, any time someone tells the truth about something someone doesn't want you to know.
Flash Player shouldn't be a factor. Get the page to load first, then you can determine if you need Flash Player. You probably don't.
If you circumvented the restriction in the past by using a different DNS, find out how you can do that again. I don't have one to suggest.