How to pass base64 string to XML file ?

byte[] videobytes = File.ReadAllBytes("C:test.wmv");
                string result = System.Convert.ToBase64String(videobytes);
           
                // Create the XmlDocument.
                XmlDocument xmlDoc = new XmlDocument();
                XmlDeclaration xmlDeclaration = xmlDoc.CreateXmlDeclaration("1.0", "utf-8", null);
                // Add a price element.
                XmlElement rootNode = xmlDoc.CreateElement("Clip");
                xmlDoc.InsertBefore(xmlDeclaration, xmlDoc.DocumentElement);
                xmlDoc.AppendChild(rootNode);
                XmlWriterSettings settings = new XmlWriterSettings();
                settings.Indent = true;
                xmlDoc.Load(result);
                // Save the document to a file and auto-indent the output.
                XmlWriter writer = XmlWriter.Create("C:data.xml", settings);
                xmlDoc.Save(writer);