YouTube Slowly Uploading High-Quality Videos - Google Blog - InformationWeek
Watching standard definition TV can be a drag. What's even worse is tuning into YouTube videos. The video quality is often lacking in a big way. YouTube is hoping to change that, however, and is beginning to make higher-definition videos available for viewing.
As both a creator for and a watcher of the videos posted on YouTube, I know what a pain it is to upload long videos. Even if you have a very fast Internet connection, long videos can take a long time to get upstream to Google (NSDQ: GOOG)'s YouTube servers. High definition (or even higher quality) video, which is often four times the data of regular video, is much worse to work with and takes far longer to upload.
Not only does it take longer to upload, but it also takes longer to process on your PC and prepare for publication to begin with. This is why most people settle for the standard "YouTube" definition. In fact, iMovie has an uploader built directly into it, and it automatically creates videos that are the correct resolution to match what YouTube can handle.
From Internet Marketing and Internet Annonsering