S4 Screen Flickers When Playing Streaming Videos or normal videos

Hello, Recently while playing youtube video,My galaxy s4 I9500 encountered an unsual issue. The screen is flickering and flashing horribly while playing youtube or videos on device. I have done a reboot and it was working fine..... again some times it started flickering while watching videos. Please suggest me what to do....solution for this problem ?? send the solution to my mail id : apmvckasi@gmail.com