[~Kizwiz~]

I've used you tube for a while now but noticed that some of the video's are really blocky and aren't as clear.

Is there a reason for this or maybe something I can do to improve it? Is it my connection speed or just the video that I have chosen?

I havent ever noticed the blockiness but its really obvious

[Matt]

It might just be the video.

Try adding &fmt=18 to the end of the URL?

[James]

Video on YouTube that have fast action will tend to be blocky. If you have a YouTube account going to My Account / Video Playback Quality and selecting 'Always play higher quality video when it's available' improves some of them. Or just do the &fmt=18 trick mentioned before.