WordCamps are a great place to jump-start your education in the world of WordPress development, or build upon yours current skills to make even greater plugins and themes. Here are some recent videos from WordCamp Asheville and WordCamp Vancouver focused on how you can polish your development skills
Introduction to WordPress Plugin Development
Jonathan Daggerhart gives a basic introduction to the creation of a new plugin, including using the Codex, actions, filters, shortcodes, custom settings, and some best practices. An existing understanding of some PHP is required to get the most value from this presentation.
How To Build A Custom Widget
Widgets are a great way to deliver added content or functionality to a WordPress site. In this presentation, Mel Karlik shows you how to create a simple custom widget then see how you can distribute theme with a theme or as a stand-alone plugin.
Advanced Custom Fields – Beyond the basics
This presentation by Merrill Mayer covers the use of advanced custom fields in non-blog oriented websites, focusing on using them in custom post types as well as demonstrating custom queries along with custom prev/next posts.