Why is my iPod nano screen turning black when I play a movie?

I have an iPod nano 5th generation. The storage capacity is 14.7 G. I downloaded three videos from iTunes on to my nano yesterday. When I first clicked the video files, the screen turned white. It was frozen. I left it over night and it died. This morning I charged it and it was fine. I tried again and after I opened the files, I clicked a video and it now turned black. I fixed this by holding down the home button and off button for ten seconds. I tried another video and the same thing happened. The last video did the same.