Cameo, a marketplace in which users pay for personalized video messages from celebrities, has gone from niche novelty to very big business. One celebrity just surpassed $1 million in earnings, and more than 5,000 messages are sold each day. Dan and Cameo CEO Steven Galanis dig into how the company came to be and how it's changing the monetization of fame. Plus: A "cameo" from one of the site's top stars and debate night analysis with Axios White House and politics editor Margaret Talev.