Walter Dal Mut gives a presentation on PHP and cloud computing. He discusses how cloud computing allows applications to automatically scale capacity up and down based on demand. This helps reduce costs by only paying for resources when needed. It also improves reliability and availability since unhealthy instances can be replaced. He provides examples of initial scalable PHP environments using a single EC2 instance and load balancer. More advanced architectures are shown using auto scaling, which launches additional instances when metrics like CPU usage increase. Auto scaling helps applications dynamically right-size to traffic without the need for manual scaling.