Yes, it's a very good idea! I often send links to friends and now they get a clue of what's behind this link just by having the title added in the URL. Nice!

Edit:
Unfortunately, it interferes with Google. When on Google search site, the script refreshes the page in an automatic loop. So I suggest to enable the script by default not for any website, but only for:

http://www.youtube.com/watch?*

…and nice realisation.