TechnoTip continue their video tutorial series: "Today lets learn to make progress bar to indicate game loading time to the user. This keeps the user informed about the percentage of assets being loaded and the wait time – this method has proved to dramatically increase the user retention rate on the page, even though it simply is an indicator of the game being loaded. Simply showing a continuously rotating circular image would turn off most users after some time. Progress bars on the other hand have always been well received – I’m telling this after digging into my analytics data."
Progress Bar Tutorial
In this TechnoTip video tutorial they cover creating and updating a progress bar.