Because:
"The official said the video of the chemical tests on the dogs suggest a very strong desire to acquire the capability to use such weapons against humans. Until now, he said, he had seen nothing that indicated bin Laden or al Qaeda had the capability. "
"This tape is unquestionable documentation that he has some capability," he said. The tape, he said, shows "some level of sophistication, and indicates they were trying to get results."
They could just tell me though. It would not be necessary to show a dog struggling for life to make the point. I think they are showing the video for ratoings not substance.