Barrington analyst Ted Moreau downgraded Ambarella (AMBA) to Market Perform saying a "number of concerns" could "put a lid on the stock" following its Q2 results. The market may remain concerned about application processor competitive threats, and the company's guidance being only in-line with consensus estimates is "not good enough" for a high-multiple stock, Moreau tells investors in a research note. Further, Ambarella will have challenging earnings growth comparisons in coming quarters and China economic concerns reduce visibility, he adds. Despite downgrading, Moreau still believes Ambarella is "very much more" than a play on GoPro (GPRO) and that the video capture market is "accelerating in new and exciting areas." The stock declined $7.63 yesterday to $81.98 after reporting Q2 results.