I will back up valuvsmk. I posted this on another board, and I'll add it here.
The Nick at Nite version was a bad imitation of an absolutely beautiful moment . The original duet occurred in 1977 if I'm not mistaken. It was a magical moment, where as val noted, Bowie delivered his first real "mainstream" performance. While they were certainly an odd pairing, their voices blended perfectly, and it is considered a classic Christmas moment. Bing died before the special was released, making the duet even more poignant. When Christmas specials are highlighted on TV, the Bing and Bowie duet is always shown as a magical moment in the history of holiday specials, and the recording, kept only from the recording done during the special (not done as a studio recording) is still played constantly at Christmas.
The Nick at Nite performance upset me a great deal--the Bing and Bowie duet is very precious to me, I skated to it at Christmas 2001 in a time of great turmoil because I truly believed in striving for peace, and I still do. Nick used a very bad "film" of Bing, and I'm sorry if I upset Clay fans by saying this, but Clay did not perform the song to the original standard--he was off tempo and badly off key more than once, and the combination of that with the bad animation made it look thrown together and frankly, tacky. I realize that Clay was probably given the "bit" to perform and had little choice in the matter, but it came off like a cheap attempt to rip off a classic Christmas moment. Clay is very talented and has a great career ahead of him, but this was not the way to show his strengths. I hope the AI people will consider letting him shine on his own merit instead of putting him in situations like this. They seem to thrive on putting their stars in bad situations intended to capitalize on their fame and make money without considering their longevity (witness Justin Guarini's short career with a bad album that didn't sell and that awful movie with Kelly). Clay deserves better than what he was given on Nick at Nite, and those of us who cherish the original performance deserved better, too.