After I've been able to sit back, sleep on it for the past few days and digest everything, I think the core issue here is the definition of "reasonable doubt", or at least the jurors' interpretation of it. Should the prosecution be required to prove exactly how a murder occurred? Should they be required to present hard evidence for a murder that occurred? Hard evidence will not exist if a body is not found in due time. Circumstantial evidence IS evidence. So while the jury decided there was "reasonable doubt" in regards to the exact events that occurred as laid out by prosecution, I find it impossible to say there is reasonable doubt that Casey Anthony was heavily involved. I also think that there was enough evidence presented that murder was committed beyond reasonable doubt. The common sense facts, of body disgarded, hidden, duct tape, AND expert testimony that said the death was concluded to be homicide. So if you prove it was a murder which I think they did, and you prove that Casey Anthony was involved through damning circumstantial evidence which they most certainly did, you HAVE to convict her of the very least second degree murder or man slaughter. These simple facts certainly were proven beyond "Reasonable Doubt".
Perhaps the prosecution faltered by trying to prove a specific series of events without the evidence to back it up. They should have just admitted they did not know exactly how it happened but focused all their power on the circumstantial facts surrounding her behavior, lies, and deception following the disappearance.
I think they also faltered seriously by trying to paint her as a villain in life when all testimony of people she knew said she was a friendly person. They also painted her parents as victims which the jury didn't buy at all. Basically they tried to spin a little too much, tried to play on emotion a little too much, and the jury perhaps realized there was too much bull to sift through and rejected the prosecution's case all together as result. The prosecutions case definitely looked like a "win at all cost" type of case instead of a "lets present truth and let the chips fall where they may" type case. I do not think this sat well with the jury.