It doesn't work well with 'bestvideo' and 'bestaudio' because they are usually before the max quality.
Format filters should be used instead, they are more flexible and don't require the requested quality to exist for each video.
* Remove the 'songtitle' field, 'title' can be used instead.
* Remove newlines in the help text, for consistency with other options.
* Add 'from __future__ import unicode_literals'.
* Call '__init__' from the parent class.
* Add test for the format_to_regex method