Effective adaptive streaming systems need informative feedback that supports selection of appropriate actions. Packet level timing and reception statistics are already widely reported in feedback. In this paper, we introduce a method to produce low bit-rate visual quality feedback and evaluate its effectiveness in controlling errors in live video multicast. The visual quality feedback is a digest of picture content, and allows localized comparison in time and space on a continuous basis. This conveniently allows detection and localization of significant errors that may have originated from earlier irrecoverable losses, a task that is typically challenging with packet level feedback only. Our visual quality feedback has low bit overhead, at about 1% for high-definition video encoded at typical rates. For live video multicast with 10 clients, our experimental results show that the added ability to detect and correct large drift errors significantly reduces the resulting visual quality fluctuations.