Will it stream VLC player?

[Tox Laximus]

I assume you can also plug a controller into steamlink to control media players?

[Daverball]

It should be able to stream any external application you have added through "Add A Game" at the bottom of your library, as long as the steam overlay works with it. As long as you're in the Steam Client it'll stream your entire desktop though, so you could potentially alt tab into vlc, although i'm not sure if it will stream the audio as well.

[Shino]

It does not have to be added to steam.
Just choose "Return to Desktop" when in Big Picture Mode and you can control your windows via gamepad. Easy.
(RT = left click, LT = right click)

[Greg]

VLC works fine. I'd recommend adding it as a steam game as the other methods often result in the resolution being way off.