"Poshmark, eBay, TikTok. [I've gotten] nonstop phone calls," Velez said. "TikTok flew in from China to meet with us." That market size might explain why some major platforms are rushing to grab a piece of the action here in the U.S. The trend involves a seller broadcasting live video of themselves showing and explaining products while viewers ask questions and make purchases in real time. Livestream shopping started on social media in China, and according to Coresight Research, has grown into a $512 billion market. "All the metrics exceed any other form of shopping I've seen – period," Velez said….