The actual URL for the scripts feed is now changed to
http://www.msgpluslive.net/scripts/feed/ which does
validate.
http://www.msgpluslive.net/scripts/browse/rss.php actually redirects you to the scripts DB itself now, I will update rewrite rules tomorrow to make it redirect to the new feed url. (urls where changed a few days ago because of an update to the site)
For the news feed GFD or Patchou will need to take a look, but looks like they'll just need to add "http://msgpluslive.net" in front of the URLs.
Thanks for notifying.