These are old feature flags that are no longer used: ENABLE_MANUAL_GIT_RELOAD was to allow instructors to reload an XML Modulestore course directly from a git checkout. That Modulestore backend hasn't existed for a while. DEBUG_LEVEL was an early flag for how debug log verbosity. USE_YOUTUBE_OBJECT_API was created in reaction to YouTube breaking their iframe API. They have long since addressed those issues.
LMS (Learning Management System) -------------------------------- This directory contains code relating to the student portal for edX.