My PBS station used to show this during their yearly donation drive, until about 5 or so years ago.

Before this special first aired (September of 2002) PBS promoted the heck out of it for months. I forgot how it was obtained, but PBS gave away packets that contained a wall poster (a real version of http://pbskids.org/arthur/pdf/backstreet/backstreet_poster.pdf) as well as a CD-ROM with video clips, three songs from the special as well as artwork. I never got one, but it definitely was an exciting time to be an Arthur fan.

The special occasionally gets posted on YouTube. I can't bring myself to watch it now, because I get depressed knowing the animation won't ever look that good again.