Nice contribution, studiof 
One suggestion, if I may, you can also control the shading of the inner (and somehow outer) corners with a few additional steps, if you'd like.
Example: from bottom to top...
http://postimg.org/image/cw0zuzgzl/
1: similar topology to the one shown in the video. Still a bit of shading issues, mainly visible for the inner (bridged) faces.
2: Quickest fix: hard edges only on the inner, concave corners (where hard edge usually are the most usefull).
3: Control edges. Same logic as the additional loops that you used, it corrects both inner and outer corners, as shown on the right, shaded view.
4: just a possible variation of 3, common in game modeling, correcting only the most needed shading, inner corners.
btw, at 2:40, you can also avoid manually selecting each of the inner faces by just selecting a vertical edge, hit 'G' which you well know already, and 'F' to convert to faces. Done.
EDIT: Just saw on the youtube comments that Micheus beat me for this last little tip already!
One suggestion, if I may, you can also control the shading of the inner (and somehow outer) corners with a few additional steps, if you'd like.
Example: from bottom to top...
http://postimg.org/image/cw0zuzgzl/
1: similar topology to the one shown in the video. Still a bit of shading issues, mainly visible for the inner (bridged) faces.
2: Quickest fix: hard edges only on the inner, concave corners (where hard edge usually are the most usefull).
3: Control edges. Same logic as the additional loops that you used, it corrects both inner and outer corners, as shown on the right, shaded view.
4: just a possible variation of 3, common in game modeling, correcting only the most needed shading, inner corners.
btw, at 2:40, you can also avoid manually selecting each of the inner faces by just selecting a vertical edge, hit 'G' which you well know already, and 'F' to convert to faces. Done.
EDIT: Just saw on the youtube comments that Micheus beat me for this last little tip already!