As Rahul Mathur states in his blog “A blog with a difference”, there is an add-on in Firefox that allows you to watch all videos on YouTube by default in high quality. How do you install the script? You need to have Firefox . To install the script, you need to install an add-on called : Greasemonkey . Once you install the add-on , go to this link and click on Install . Rest shall be self explanatory. Just install this script and you get every video in high quality plus you get to see HD video without refreshing the window as the script uses AJAX. – I checked it out and it works, that’s a great advice!