IINA is now available. A modern media player crafted for macOS and a good alternative to VLC. The app is from the ground up developed to make use of modern technologies and frameworks available in macOS such as Force Touch, Touch Bar, and Picture-in-Picture.
Plays anything
Just as the open source alternative VLC, IINA plays almost everything you throw at it. It uses the open source media player mpv and supports youtube-dl, via extensions it supports various one click streaming.
Open source
IINA is under active development using the modern Swift programming language. Its free and open-sourced under the GPLv3 license.
Go check it out yourself here: IINA