How has the court determined that there was a knowing and voluntary waiver of her rights?

Sixth, the trial court reviewed the videotape of the second interview and assessed defendant's demeanor. In the trial court's view, her demeanor and the way she answered questions supported the inference that there was a knowing and voluntary waiver of her rights. The appellate record does not contain a copy of the video. This means that nothing in the appellate record contradicts the inference, and we cannot second guess the trial court. (Denham v. Superior Court (1970) 2 Cal.3d 557, 564 ["All intendments and presumptions are indulged to support it on matters as to which the record is silent, and error must be affirmatively shown]".)

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