As no one else has responded, I will comment.
For a newbie, you have been very adventurous with your thermal scope !
The modified firmware was developed using what could best be described as a risky process. It was the result of one persons differential analysis of the FLIR Scout scope firmware and that of a FLIR based thermal vision rifle scope. The firmware of the Scout was then modified to contain additional elements from the rifle scope version without a full understanding of the changes. Such an approach is risky and as the firmware is not understood, it can be difficult to rectify issues. It is classed as blind hacking of firmware in my world and very risky. This is why your firmware does not behave perfectly and some functions appear unstable.
The other issue with this approach to firmware modification is that it can be very difficult, or even impossible to revert to the stock (stable) firmware.
The SCOUT firmware and configuration has not been reverse engineered and cannot be manipulated as easily as that in the E4 camera. The modified firmware that you have used is the only one known to me and I chose not to use it due to its risky development process. If you kill the firmware on a Scout through an incorrect change, you can render the unit useless, requiring return to FLIR for a Firmware reload. Be careful if you decide to change anything in that hybrid firmware that you are running. Some might call that 'hacked' firmware a kind of Frankensteine's Monster of firmwares. The result of grafting different versions together.
The Video output on the USB socket was standard on the Scout II series so I would have expected it to be present on your unit if it is a series II chassis inside. It is a hardware difference to the MK1 Scout scope that only outputs video from the base contact.
Fraser