Easy access to low-cost, high definition video technology has transformed how researchers and practitioners are approaching school improvement efforts. Video-based observations of classroom instruction provide researchers the means to define and measure aspects of effective teaching and suggest subsequent professional learning. In this article we describe three use cases for video observations based on the work we are doing at the Center for Education Policy Research (CEPR) at Harvard University. The cases discuss strategies for (1) using teacher videos to improve instructional practice through 1:1 coaching focused on the use of a mathematics-specific observation rubric, (2) making observation and feedback cycles practical for over-burdened principals, and (3) developing outcome measures to inform our understanding of teacher effectiveness and suggest the potential for improvement. We describe a research agenda that is grounded in concrete examples of teaching practice.