TIL about the openwith package. It enables Emacs to defer to external programs for certain files. You choose which ones. Neat.
(use-package openwith :ensure t
:config
(csetq openwith-associations
'(("\\.\\(mp4\\|mp3\\|webm\\|avi\\|flv\\|mov\\)$" "open" (file))))
(openwith-mode 1))