Marissa Mayer says Google collects information about users' activity to improve the quality of search results, not to create a profile for each user. They need to store it for an indefinite period of time as there are services that require a huge quantity of data to process, like the spell checking feature on Google Search.
The documentary puts tough questions like: "How can you convince people that Google isn't a Big Brother company?", "Can we see how do you scan the books?", "Should the digitization of books be made by a company like Google who may require fees to query the database for a research project?", "What happens if a search engine becomes dominant?".
The conclusion of the documentary? Google shouldn't be let to become a monopoly, they shouldn't be the only source of information, they shouldn't become the Ministry of Truth. Although Google's neutrality and unbiased results are a proof that it deserves our trust, it's always the best to diversify the sources of information.
And here's the full video: