I have the below code and it is not executing, can I have some input on what is wrong with it?

Error is: You must provide at least one URL. https://prnt.sc/Alvh7tcO0bsp

string commandarg = "-f " + textBox1.Text.Trim();
                ProcessStartInfo processInfo = new ProcessStartInfo
                {
                    FileName = ConfigurationSettings.AppSettings["youtubedlpath"].ToString(),
                    Arguments = commandarg,
                    UseShellExecute = false,
                    RedirectStandardOutput = true,
                    CreateNoWindow = false
                };

                using (Process process = new Process { StartInfo = processInfo })
                {
                    process.Start();

                    // Synchronously read the standard output of the spawned process.
                    StreamReader reader = process.StandardOutput;
                    string output = reader.ReadToEnd();

                    // Write the redirected output to this application's window.
                    Console.WriteLine(output);
                    
                    process.WaitForExit();

                    if (!process.HasExited)
                    {
                        process.Kill();
                    }
                }

                Console.WriteLine("nnPress any key to exit.");
                Console.ReadLine();