WebCamTexture.isPlaying

Возвращает, если камера в настоящее время воспроизводит.

using UnityEngine;

public class Example : MonoBehaviour
{
    // Tries to start the camera and outputs to the console if is was sucessful or not.
    void Start()
    {
        WebCamTexture webcamTexture = new WebCamTexture();
        webcamTexture.Play();
        Debug.Log(webcamTexture.isPlaying);
    }
}