Videos buffer in order to avoid packet loss when streaming content. If your video is continually buffering, then most likely your connection is too slow for the content you are attempting to watch. If at all possible, attempt to use a lower resolution form of the video. For example, you can choose the quality of a YouTube video by choosing 360P instead of 480P. Other video players will have similar options.

Better Internet, more Ram and download Reginout to fix this issue.