Not sure about making a shortcut icon on the home screen for an URL but, for YouTube, download the YouTube app...it's SOOO much nicer than going to the mobile YouTube site.
After you DL the ap they will be in your applications folder. Highlight it and hit the BB button once select Move to Folder and choose the Home folder. This will put the icon in your home view, you can then move it around as you wish.
Not sure about making a shortcut icon on the home screen for an URL but, for YouTube, download the YouTube app...it's SOOO much nicer than going to the mobile YouTube site.