I just watched the entire defense closing on YouTube. It took about 4 hours. I can easily see now why the jury couldn't vote to convict. There was no evidence of how Caylee died, who killed her, or motive. There was certainly plenty of doubt created by the defense's theory that she may have drowned (the picture of Caylee opening the back door by herself, the strange statement by the grandmother to her co-workers, the pull-ups and no socks or shoes found on the body, etc.). The duct tape with the logo on it that was found on the body that lined up with the grandfather's duct tape captured on video by the news crew at the "command center." The strange story and lies about the gas can with that same kind of duct tape on it. The bizarre story of the guy who found the body and his changing story.
Lots and lots of doubt. I simply don't see how you can convict for murder on that. I don't doubt that Casey knows much more than she's ever told, particularly about the way the body was disposed of, but that's not a reason to convict her of murder, manslaughter, or child neglect.