We use an example of runners, and the main runner page is seen by logged in users, but there are runner specific child menu items that are only seen by those specific runners...no other runners can see their pages. This may be a scenario where coaches have special and secret training plans for certain runners, and that information shouldn't been seen by other runners.
The groups are created, followed by access levels, menu items and articles are tied to those Joomla access levels, then users are assigned to the groups. The video walks through the backend creation, front end example of Joomla access control on specific menu items, then a re-cap in the backend.
I hope this video helps others, as it did help with a specific need on our development. Thank you...Sol Web Solutions (http://www.solwebsolutions.com)