I want to reduce the file size of a bunch of videos at once on my Mac.
Would you know any free tool that does that or any way to automate a loop in Automator to pilot Handbrake to loop on a given folder?
Handbrake can queue up a batch of files.
FFmpeg is free and works on a mac, but you'd have to run it from Terminal. You can install it using Homebrew for Mac.
Once Homebrew is installed, go to Terminal and type
brew install ffmpeg
Then you should be able to change directory to wherever your files are by typing something like:
where my.username would be your username on that mac, and Movies would be whatever directory the files were in
Then you can convert them by typing something like
ffmpeg -i input.mp4 output.webm
Where input.mp4 is your source file, and output.webm is your output file.
To convert all the mp4 files in that directory you would enter
ffmpeg -i *.mp4 output.webm