Add rule to pick up theme videos

Emby.Naming/Common/NamingOptions.cs

@@ -470,6 +470,12 @@ namespace Emby.Naming.Common
                     " sample",
                     MediaType.Video),
 
+                new ExtraRule(
+                    ExtraType.ThemeVideo,
+                    ExtraRuleType.DirectoryName,
+                    "backdrops",
+                    MediaType.Video),
+
                 new ExtraRule(
                     ExtraType.ThemeSong,
                     ExtraRuleType.Filename,

tests/Jellyfin.Naming.Tests/Video/ExtraTests.cs

@@ -53,6 +53,7 @@ namespace Jellyfin.Naming.Tests.Video
         [InlineData(ExtraType.Sample, "samples")]
         [InlineData(ExtraType.Clip, "shorts")]
         [InlineData(ExtraType.Clip, "featurettes")]
+        [InlineData(ExtraType.ThemeVideo, "backdrops")]
         [InlineData(ExtraType.Unknown, "extras")]
         public void TestDirectories(ExtraType type, string dirName)
         {