Snapchat isn't the new kid on the block anymore, but it's still the youngest of the four major social players fighting for ad dollars. And while it might not attract the largest share of social spend, many of its advertisers are reaping the benefits of the less-crowded, low-cost platform. eMarketer's Tricia Carr spoke with Arielle Vogelstein, growth principal at ride-sharing app Via, about why Snapchat advertising is the right choice for the company, and why it plans to spend more on the platform.