Back button is not working properly

[brinder]

When the back is pressed from fullscreen while a video is playing, video gets struck.

[Myerden]

To accomplish this feature, we should simulate the 'exit full screen' click from webView. What I mean, when user press back button , it should exit the fullscreen like clicked the video's fullscreen button.
to do this follow these steps;

First Step

Embed this javascript code inside your webView element.

<script>
function exitFullScreen() {
	if (document.exitFullscreen) {
	  document.exitFullscreen();
	} else if (document.msExitFullscreen) {
	  document.msExitFullscreen();
	} else if (document.mozCancelFullScreen) {
	  document.mozCancelFullScreen();
	} else if (document.webkitExitFullscreen) {
	  document.webkitExitFullscreen();
	}
}
</script>

** this code should be inside the html body tag.

Second Step

Use boolean value to know if the video is in fullscreen mode.

My activity like this;

public class PostDetailActivity extends AppCompatActivity 
	implements VideoEnabledWebChromeClient.ToggledFullscreenCallback{

private boolean fullscreen = false;
// some code

in here we save the fullscreen situation

@Override
public void toggledFullscreen(boolean fullscreen) {
	this.fullscreen = fullscreen;
	// Your code to handle the full-screen change, for example showing and hiding the title bar. Example:
	if (fullscreen)
	{

Third Step

Call this javascript exit function from activity when back button is pressed;

@Override
public void onBackPressed() {
	if (fullscreen){
		postWebView.loadUrl("javascript:toggleFullScreen()");
		fullscreen=false;
		//webChromeClient.onHideCustomView();
	}
	else
	{
		postWebView.onPause();
		super.onBackPressed();
	}
}

https://stackoverflow.com/a/21281249/4133449