Hey Jose. The inner container is necessary when you don't want your content to span edge to edge on a browser, but rather within your site container width.
Flex is a huge innovation and I cannot believe how few videos there are that fully explain how to use it. This was great (not at all "all over the place") and I look forward to seeing the full design video you mentioned. Keep up the good work. Philip.
Thanks for the well timed video. I was just thinking yesterday that I need to get my head around switching from using the GenerateBlocks grid to Containers and Flex. Very useful!