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.
XPath with recursive children selection not supported
For more information, see #5498 and changes to convertObj() in iustin/pyxattr@cc84e466f6
Caused by commmit 592e97e855
592e97e855
The gdata api V2 was deprecated and according to http://youtube-eng.blogspot.com.es/2014/03/committing-to-youtube-data-api-v3_4.html remains available until April 20, 2015.
extract_videos_from_page
load_more_widget_html
There isn't any problem if the 'formats' field only has one element