How to run FFMPEG at my web host server

Question

I want to perform some video process at my web host server. I don't think the web host server will allow me to execute an exe file for security reasons.

Should I use SharpFFMpeg?

I have downloaded SharpFFMpeg. But it's lacking a proper documentation.

Can someone give one example how to perform a conversion from one video format to another?

I have written my execution program, but the compiler says it cannot file the file specified. What's wrong with it?

        string command = @"D:\Recorded TV\ffmpeg.exe -i ""Australia's Toughest Police_QUEST_2013_04_17_21_57_00.wtv"" -s 800x400 throughCS.mp4";
        try
        {
            ProcessStartInfo psi = new ProcessStartInfo("\"" + command + "\"");
            psi.RedirectStandardOutput = true;
            psi.UseShellExecute = false;
            psi.CreateNoWindow = true;
            Process proc = new Process();
            proc.StartInfo = psi;
            proc.Start();
            string result = proc.StandardOutput.ReadToEnd();
            tb1.Text = result;
            Debug.WriteLine(result);
        }