The only network that has the tape is ABC, that's why it has not shown up on any cable channel.
ABC thinks the political implications of airing the tape right now might outweigh its news value. (IOW, it might help Bush by reminding voters the WOT is real.)
My e-mail to ABC News:
There's a really bizarre rumor going around. People are claiming ABC News has a tape of a terrorist making horrible threats against The U.S.. They say the tape has been authenticated by authorities but ABC will not report on it because it might harm John Kerry's Campaign. This is obviously an urban myth as I see no mention of it in your reports and I KNOW ABC would never do anything to favor one candidate over another. Please let me and the public know this is only a rumor.
I read on one of the blog site, Jay Nordlinger, I think, that some other news organization has been offered the same video that ABC has because whoever is in charge is upset that ABC hasn't shown it yet. Supposedly, this other news organization has contacted CIA/FBI for advice about whether to show it.
If anyone has the tape, in my opinion, and showing it could possible save lives, that person/news agency has a moral duty to show it.