Fix Seiga sample/thumbnail rewriting

app/logical/downloads/strategies/nico_seiga.rb

@@ -30,9 +30,10 @@ module Downloads
       end
 
       def rewrite_thumbnails(url, headers)
-        if url =~ %r{/thumb/(\d+)}
-          id = $1
-          url = "http://seiga.nicovideo.jp/image/source?id=" + id
+        if url =~ %r{/thumb/\d+}
+          source = ::Sources::Strategies::NicoSeiga.new(url)
+          source.get
+          return [source.image_url, headers]
         end
 
         return [url, headers]

app/logical/sources/strategies/nico_seiga.rb

@@ -89,6 +89,8 @@ module Sources
             "http://seiga.nicovideo.jp/seiga/im#{$1}"
           elsif url =~ %r{\Ahttp://lohas\.nicoseiga\.jp/priv/(\d+)}i
             "http://seiga.nicovideo.jp/seiga/im#{$1}"
+          elsif url =~ %r{\Ahttp://lohas\.nicoseiga\.jp//?thumb/(\d+)}i
+            "http://seiga.nicovideo.jp/seiga/im#{$1}"
           elsif url =~ %r{/seiga/im\d+}
             url
           else