I’ve always wondered about using HDMI as a data exfiltration path. To the best of my knowledge, there are security tools monitoring for employees plugging in USB drives or connecting to Google drive, etc, but none which are watching the video output. You could easily hide the data transfer such that someone looking at the screen remotely wouldn’t notice the data transfer.
My understanding of the motivation for this (really neat) hack is that cheap FPGA boards lack IO pins to interface to USB3 interface chip and external components (i.e. parallel DAC) at the same time. Seems like these boards tend to have built--in connector that uses up the GPIO pins.
Wonder then if it's possible to use the HDMI port to connect a custom board with the USB3 chipset. Maybe the crosstalk between the wires is too high.