First off, we don't know what the tapes had or why they were destroyed so you can calm down. Second, looking at the past there is another example of the CIA destroying interrogation tapes. In the previous case it had nothing to do with torture and everything to do with politics.
Apparently US interrogators dressed up like Saudis, where even the most brutal methods we use would be like a massage at Club Med in comparison, since usually that is enough to get terrorists to break down and talk. This high level terrorist instead gave the phone numbers of 3 Saudi princes and a Pakistani general and demanded to be released. The 4 died within a week and the tapes vanished when Congress asked the CIA for them to verify if that is what happened.
If I'm not mistaken the current tapes are of the interrogation of high level terrorists which means it much more likely that the tapes show them naming their contacts in Saudi Arabia, Pakistan, or other Mideast countries than the terrorists being tortured.
Thirdly, given the complete and utter incompetence of the CIA I would be surprised to learn that they a) know how to torture correctly, b) can destroy a video, and c) most importantly they can keep it secret. You've got serious problems when even the IAEA is more hawkish on the greatest current threat to global security.
Fourthly, as has been mentioned dirty things must be done to maintain civilization. The moment we stop is the moment we lose civilization. Europeans used to understand that when they were on top of the world but I suppose it's easy (convenient?) to forget that when someone else is on top. Indeed one of the major problems today is that the US tries to be too clean about everything rather than just doing what needs to be done like Europeans used to.
