ummm i didnt mix up anything everything was well explained semitones that's just a half steps its the same thing so idk what your talking about general music theory can be broken down into all the following listed in the vid anything beyond that can be considered a more advanced study like jazz theory for instance the purpose of the video was to give general overlay as from there im assuming you can do the rest of the research on your own. Honestly if I REALLY wanted to get into i could have explained it on a fundamental physics based level looking at transfer functions , digital signal process(the field of study), harmonicas ect BUT for the conventional person i discussed more than enough music.