You can think, how much would their marketing team have to spend to get the same results that the algorithm contract gave. I'm not a marketing expert, but I'm sure they have metrics like consumer sentiment, name recognition, number of users visiting the site, google search trends, etc. There could also be benefits in recruitment, and that can be estimated based on how much you'd have to pay an external recruiter to bring in candidates the applied, or other things like that.
It was in the news a lot, and was discussed on a lot of tech sites. Plus it gets people talking about their recomendation algorithm, and makes people thing Netflix subscription is more valuable becasue it recommends good shows. It wouldn't be cheap to get the amount of media that they got through more traditional marketing.