What I saw on the video is that she looked very angry with him. Her body language and the look on her face told me they were in some sort of confrontation at the time.
I just saw a moody teen, you see them everyday, and knowing now she didn't have her cell phone and thinking she was pissed about that, and thinking she was in the midst of telling some big lies, I didn't recognize real strange behavior towards the Uncle.
It is so forked up and diabolical if he took her in the convenience store just with the purpose of getting her on video. It's all quite strange if the Uncle is the perp.