UnityEngine.VR.WSA.WebCam Not Found During Build

I tried to use Unity VideoCapture API, which is located inside UnityEngine.VR.WSA.WebCam namespace. In Editor mode I can play the scene without getting any error, but when I tried to build it for Windows and/or Mac, I got error that said UnityEngine.VR.WSA.WebCam namespace not found…

What is wrong? FYI, I use Unity 5.6… Thanks in advance…

Same problem Using Unity 2017.2.0f3

For Unity 2017, I found the same header under

UnityEngine.XR.WSA.Webcam;

That’s the only small change.

Same problem Using Unity 2018.1,Same error in unity 2018.1