I feel like he might've ensured the external situation was set up to his liking before entering the house and abducting Nancy. Since he hadn't been inside yet, he comes around from the side of the house.
Check out the flashes/reflection on his right wrist right at the start of the video (00:01, while his head's still down) and after grabbing the lantana (00:28). He seems to be sneakily checking a device on his wrist before the entry and reentry of the porch.
I'm wondering if he wasn't wearing a
deauth watch.
View attachment 647616
This device can disable WiFi and jam WiFi cameras. He checks it each time to make sure it's still jamming before approaching the porch.
Maybe he got a cheap model that doesn't jam 5 Ghz, which the Nest Doorbell can utilize. Or maybe he did jam the camera, but at some point the jamming stopped, the Nest reconnected to the WiFi, and uploaded the video we see to the Nest servers.
That's why he's not being as fastidious with hiding his face as you might expect considering the gravity of the crime.
Just a guess.