Yes, and it is possible that BI was (perhaps) simultaneously trying to access the camera with the old password that caused my problem. I am not sure. In the future I will shut down BI completely before attempting a Dahua password change.
I changed the password, but I left the username as "admin." You have to be careful on some cameras because they have two admin accounts -- as one is assigned to ONVIF usage.
Isn't a VLAN just a logical mapping of network traffic? It doesn't actually "isolate" anything? So a malicious software or devious user would not be bound by the VLAN partitions.