how HD can this youtube get to????!!!

i think most of people have been living along google youtube for a while. having doubted that how hight definition Youtube can get to, i went to google's offical site on youtube where i can find many LONG and HD videos. the computer i am using is a out of date one. but has a video card on it.

then i started watching the video. here is the hyperlink in case you dont have it on hand , http://www.youtube.com/google#p/a/u/0/5JyFbF7QFlY.

here is the sample snapshot i got from the fullscreen mode.

 as we can see, even this 128Mb video card is not able to display this video clearly and smooth enough. and how fast is the loading speed? this video is more than one hour. and it only took me less than 3 minutes to finish loading all of it.