WebView has a method in API 11+, onPause. You just need to call this method when Activity onPause, and the system will automatically pause the content played in all web pages. If you install it under a version lower than API 11, you can use reflection. Call this method

I write directly like this every time, and basically I have never encountered a problem like yours. I suggest you give it a try.

    @Override
    protected void onResume() {
        if (mWebView != null) {
            mWebView.onResume();
        }
        super.onResume();
    }

    @Override
    protected void onPause() {
        if (mWebView != null) {
            mWebView.onPause();
        }
        super.onPause();
    }

    @Override
    protected void onDestroy() {
        if (mWebView != null) {
            mWebView.destroy();
            mWebView = null;
        }
        super.onDestroy();
    }