Hi,
The videos are older and some things do change over time. The differences in Web.config mainly have to do with .NET 4 doesn't require some of the things that were required in Web.config in .NET 3.5, those videos were made during the .NET 3.5 days. We still support .NET 3.5 and those settings do still exist in the web.net35.config files, but main development is in .NET 4 and we cannot have those things in Web.config for .NET 4.
Other changes to consider are that we are using a newer more flexible set of container elements that did not exist at the time those videos were made. Features that ship with mojoPortal have been updated to these panels and the source code for features included with mojoPortal is still the best example code to study.
Hope that helps,
Joe