It can be hard to find a site that isn’t shareware spam. Try this list, find a freeware you like that hopefully uses FFMPEG, and bookmark the site for next time you need a pre-vetted list of good tools:
https://www.videohelp.com/software/sections/all-in-one-video-converters
Are you Taliban and want someone dead, but frustrated with your fundamentalist movement’s pesky adherence to the rule of law? Upset at the heretic you can’t quite get proof of? Overbearing parents trying to arrange another marriage?
With new Taliban Ban on Images of Living Things®, you are back in the driver’s seat. Just take a picture of your target. After it’s done, the authorities will be practically begging you to murder that person to prevent the inevitable consequences, including the collapse of society and the rending of the fabric of space-time.