How do I stop a youtube video from stopping?

Everytime I go to a video on youtube, it'll play for a little while and then it will stop. When I try to fast foward it, it wont let me. It doesnt buffer, it just stops completely and the only way I can get it to play again is refresh the page but when I refresh it, it'll play for a little bit but it will stop again. How do I fix this?