Matt Tesauro discusses the evolution of application security (AppSec) by integrating agile, DevOps, and CI/CD methodologies into security practices. He emphasizes the need for custom AppSec pipelines that enhance workflow, improve feedback, and promote continual experimentation, with a focus on automation and metrics to reduce friction and increase efficiency. The document highlights the benefits of AppSec pipelines, collaboration tools, and the importance of scaling security practices using containerization.