What they are doing is called “double sytem sound recording”. It comes from the world of film, where the camera did not/could not record sound and a tape recorder (like a nagra reel to reel, or more recently, a DAT recorder) was used. You would then sync up sound with picture in post production.
You do double system sound in video for a variety of reasons, including being able to record better sound quality then what the camera can record.
[Arty] “are we doing it wrong…”
No. There are many ways to do things. That you are using a boom has probably improved your audio more than recording to an external deck.
[Arty] “is there a better way to do it.”
There’s always a better way 😛
[Arty] “so much information to learn so little brain cells to attach it too.”
That’s true for everyone starting out. As you increase the number of “production” brains cells you have, the more information attaches. Don’t worry about what others are doing, especially from what you see in a photo. It’s the quickest way to over-complicate things. Focus on the needs of your production, and remember everything serves the story. Without good and interesting content, everything else is fairly irrelevant.