Spotify stock is on fire, and new growth engines like advertising are becoming a bigger part of the company's growth.Spotify's (SPOT 0.20%) stock is on fire over the past two years, in large part because the company was able to increase prices and lower costs, driving vastly improved cash flows. But for the stock to continue its run, the company needs advertising and tickets/merchandise to play a role in the business. In this video, Travis Hoium covers the company's growth and where Spotify will go next.*St ...