Added detection of already downloaded file

YTdlp.cs

@@ -75,6 +75,7 @@ namespace ytdlp_gui
 
             files = new List<string>();
 
+            this.already_downloaded_regex = new Regex(@"\[download\]\s+(.+) has already been downloaded");
             this.download_regex = new Regex(@"([0-9.]+)%\s+of\s+([0-9.]+)(\w+)\s+at\s+([0-9.]+)(\w+\/\w+)\sETA\s(\d+:\d+)");
             this.download_finish_regex = new Regex(@"([0-9.]+)%\s+of\s+([0-9.]+)(\w+)\s+in\s+(\d+:\d+:\d+)\s+at\s+([0-9.]+)(\w+\/\w+)");
             this.merge_regex = new Regex(@"Merging formats into ""(.+)""");
@@ -95,6 +96,13 @@ namespace ytdlp_gui
                 }
                 line = line.Trim();
 
+                Match match = this.already_downloaded_regex.Match(line);
+                if (match.Success)
+                {
+                    file = match.Groups[1].Value;
+                    break;
+                }
+
                 if (line.StartsWith("[info] "))
                     ProgInfo(line.Substring("[info] ".Length).TrimStart());
 
@@ -189,6 +197,7 @@ namespace ytdlp_gui
 
         private readonly Process process;
         private readonly CultureInfo ci;
+        private readonly Regex already_downloaded_regex;
         private readonly Regex download_regex;
         private readonly Regex download_finish_regex;
         private readonly Regex merge_regex;