There are a few things, a lot of it requires tweaking however. Things like better smooth motion and subjectively better colour representation.
It's just a simple does what it says video player, just about every application I use is intended to be lightweight and do what it does best, mpv (in my experience) runs lighter and with less hiccups than vlc.
Also it has youtube-dl built in so you can do for example:
mpv 'https://www.twitch.tv/beergamesbeer' and it will play a stream.
or mpv 'https://www.youtube.com/the-gibberish-that-is-a-utube-url' and it will play a youtube video.
This also extents onto 90% of video content on most websites.
The second, youtube-viewer, is run in a terminal. you search and launch videos using it and they open in your default media player.
The twitch one is a gui application that lets you browse twitch without having to use a web browser, and again, opens the stream in your media player.
I'm not sure if its apt for windows users, but dmenu and in particular dmenu-extended is an amazing application for launching programs, oppening files, searching the web. (the last two options require dmenu-extended)
its a pop-up launcher that you open with a hotkey, start typing what you want, and then hit enter when its got it. My favourite launcher by far.
The reason this may pertain to windows users is many are accustomed to the winkey+type what you want method of oppening applications.
...However iirc unity has this feature built in, same with gnome and perhaps others.. I just like dmenu because its super light weight.