As above, I believe BjornB updates it. However, not enough has changed in the game to make the videos on page 1 useless and outdated. There are some nuances added over the last year through TFV and patches. But largely they all still apply. After the release of the next patch/dlc the air war tutorial videos will likely be obsolete.
I dont know if this belongs here but let me share anyway: http://www.hoi4factorycalculator.org/divisioncalculator
I made this webapp so I can understand/plan the production process better. If used correctly it can give you a nice advantage in singleplayer and multiplayer. Maybe its also useful for you.