Flash and YouTube have been iffy for years. Many TV makers have found it difficult to implement Flash since Adobe dropped it for their platforms years ago. If rebooting fixes it, then that may be as good as it gets.
Sorry to write the bad news.
I was watching YouTube on my smart TV, suddenly I saw negative like video with white images on the screen. I exited from YouTube and looked at TV (set top box connected with HDMI ) it also showed the same type of video but menu and other imges was shown nice. Then I turned off and on it again everything was good. Its been only 2 month I bought the TV.
Is this because my display panel is going to damage or it is software issue ? Why this happened?