On some occasions due to the slow speed of your internet, it is not possible to watch a video from YouTube with high quality, but you can play a lower quality version easily, yes its .3Gp I am talking about.
Learn How To Download a YouTube Video
Its very easy, you need a web browser, vlc media player and latest versions of flash player installed(no need for chrome users)
Just select the video, that you want to play(actually every video got a unique id no. and we need that.)
Now at the address bar paste this url
just change the VIDEO_ID with your video id code and press enter
Now right click on the thumbnail, and copy link address
its like 75% of the work is completed, rest is just as simple as it can get.
Now paste the url there in the box, Then select and press the play button.
Press Alt+p together
Wait and see, the video is playing. Don’t complain about the quality, its .3Gp and its like that!