1. clone the aur repo, no you cant use your aur pacman wrapper* because you need to manually download the files from black magic and put it in the directory of the pkgbuild then run the install
2. make sure youve installed an alsa plugin for your pulseaudio!
3. okay so now you can start editing****** (so you cant use h264/h265/hevc and you cant use aac, and a handful of other combinations of codecs and file formats)