fix #520

Author: nilaoda

BBDown/BBDownUtil.cs

@@ -555,7 +555,7 @@ public static async Task<string> Get302(string url)
         private static char[] InvalidChars = "34,60,62,124,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,58,42,63,92,47"
                 .Split(',').Select(s => (char)int.Parse(s)).ToArray();
 
-        public static string GetValidFileName(string input, string re = ".", bool filterSlash = false)
+        public static string GetValidFileName(string input, string re = "_", bool filterSlash = false)
         {
             string title = input;
 

BBDown/Program.cs

@@ -989,7 +989,7 @@ private static string FormatSavePath(string savePathFormat, string title, Video?
                     "audioCodecs" => audioTrack == null ? "" : audioTrack.codecs,
                     "audioBandwidth" => audioTrack == null ? "" : audioTrack.bandwith.ToString(),
                     "apiType" => tvApi ? "TV" : (appApi ? "APP" : (intlApi ? "INTL" : "WEB")),
-                    _ => key
+                    _ => $"<{key}>"
                 };
                 result = result.Replace(m.Value, v);
             }