Code and image to watermark videos.
Tested on a Mac.
Use homebrew to install ffmpeg
brew install ffmpeg
Run this command to water mark you MP4 file
ffmpeg -i inputfile.mp4 -i LondonAerospaceWatermark.png -filter_complex "overlay=1000:525" outputfile.mp4
Works with videos size 1280:720. For other sizes you'll need to change the overlay numbers to get the position right.