They don't have to go to any lengths, there is a system in place called Content ID which will find similar audio or visual material: http://www.youtube.com/t/contentid then automatically submit the take down. But there have been other reports that some companies interns have been given the take down task, and then it's just whatever they are able to find in whatever time they're alotted. It could be Lucasfilm giving the mandate to these other companies, who knows what's in those contracts.
It's great that google has added: http://www.google.com/transparencyreport/removals/copyright/ but they've blocked many of their search tools from being used in the database. For all the advance the internet has made putting information up, it'll be a fraction of the time to take it off search engines. Maybe it'll be better with everything working as a