Added more docs

lib/Web/oEmbed.pm

@@ -154,7 +154,9 @@ oEmbed provider endpoint and parse the response. The method returns an
 instance of Web::oEmbed::Response.
 
 Returns undef if there's no provider found for the URL. Throws an
-error if there's an error in JSON/XML parsing etc.
+error if there's an error in JSON/XML parsing etc. (Note: I don't like
+this interface because there's no cleaner way to handle and diagnose
+errors. This might be changed.)
 
 C<format> optional parameter specifies which C<format> is sent to the
 provider as a prefered format parameter. When omitted, the default
@@ -228,6 +230,16 @@ or C<rich> response.
 
 =back
 
+=head1 TODO
+
+Currently if you register 100 providers, the I<embed> method could
+potentially iterate through all of providers to run the regular
+expression, which doesn't sound good. I guess we could come up with
+some Trie-ish regexp solution that immediately returns the
+correspondent provider by compiling all regular expressions into one.
+
+Patches are welcome on this :)
+
 =head1 COPYRIGHT
 
 Six Apart, Ltd. E<lt>cpan@sixapart.comE<gt>