If you want to see YouTube with a higher quality (better video resolution & sound), you just have do to this:

copy : &fmt=18 ... to a video link

eg:

CaptivAte CHIKAI (edit)

http://www.youtube.com/watch?v=5T7Cbw1nmyQ

CaptivAte CHIKAI (edit) -WITH  &fmt=18 -you will notice the changes-

http://www.youtube.com/watch?v=5T7Cbw1nmyQ&fmt=18

To read a better explantation, I recommend you click to this link. 

Goodbye (^^)v 

First one says broken :(

Fixed.

It was a problem with the html tags in the first post.

Here comes another example:

LOVE AT FIRST SIGHT - Kylie Minogue:

http://www.youtube.com/watch?v=oBi0p4gRcDY

LOVE AT FIRST SIGHT - Kylie Minogue: (with &fmt=18)

http://www.youtube.com/watch?v=oBi0p4gRcDY%20&fmt=18

Goodbye (^^)v

Thanks :)

This really works! ^_^

Or I can just click the "Watch in High Quality" button, right?

EDIT: I see now that the older videos don't contain this. 

Yeah, many of the older videos don't have that option :(

It would be nice if somehow they did.