I had some issues with connecting through ftp in RNDIS mode with windows 10 x64 so I thought I'd share what I did. I downgraded from 3.12.0 to 3.9.0 so far, and already can connect through ftp on wifi with the original flir/3vlig login.
I put it into RNDIS mode. Then using ipconfig, it showed something like INFRARED as the DNS suffix and had 192.168.1.1 as IPv4 address and Default Gateway as 192.168.1.2. It wouldn't connect, so I cycled power on my computer and camera. When reconnecting, the suffix is now blank, so is the ip address and gateway. So I read to set static IP as 192.168.250.1 then connect with 192.168.250.2. Using other IP addresses will not work. So after figuring that out, it turns out Anonymous login works while the original user/pass of flir/3vlig does not work.
EDIT: Problem though, FLIRvers.rsc does not pop up. I was able to copy the file using Wifi but not RNDIS.
also, I found in the log for flir as username. "331 User name okay, need password."(< it'll say the same for whatever I type) So, is there a different password for RNDIS? I also made sure that FLIRInstallNet shows "Ethernet 2 - 192.168.1.2" in case I had to use it.