The only desperation I hear in this tape comes from the Detectives...sad!
But, IMO, the reason the DT can't use this tape to prove their version of events is because her lying started before Caylee died, not after. And she admits to the lies (at least I thought I heard her agree with LE that she's been telling them lies).
Man ICA's dagger stares towards Yuri are fierce and getting fiercer.