@functions{

    public static string Base64String(string url)

    {

        try{

            var location = Server.MapPath(url);

            System.IO.FileStream file = System.IO.File.OpenRead(location);

            System.IO.BinaryReader Binary = new BinaryReader(file);

            byte[] bytes = Binary.ReadBytes(Convert.ToInt32(file.Length));

            string base64String = Convert.ToBase64String(bytes);

            return base64String;

        }

        catch{

            return "";

        }

    }

}

输出

<video controls="controls" autoplay="autoplay" style="width:1200px;"><source src="data:video/mp4;base64,@razor.Base64String(url)"  type="video/mp4"></video>