While the official description does acknowledge the use of FFMPEG.EXE by this program unless the license of this program is GPLv3 compatible (there is NO indication that the license for this is GPLv3 compatible) it is still illegal and is pirating the FFMPEG binaries as the ones they use are compiled with GPLv3 license options enabled. They should recompile them to use LGPLv3 options and include a copy of the LGPLv3 license text. There is no license text displayed and requires acceptance during the install process so it’s absolutely NOT GPLv3 licensed or licensed in a compatible manner.