This is a great deal for both sides.
Brown is currently on a 2 way deal that sees him earn just $100k in the AHL. Capfriendly estimates his current career earnings at $1.15M. That should creep up closer to $1.5M if he can stick on the NHL roster, but is still very modest by NHL standards. While this possibly leaves a couple hundred grand on the table if he sticks as a full-time NHL player, it offers major financial security by ensuring that he gets $750k next year no matter what. That's over 50% of his career earnings so far and goes a long way toward ensuring his financial future.
For the team, this gives us another year at league minimum against the cap. Next year is going to be a cap crunch and we need cheap depth. It doesn't get any cheaper than this. The only risk is that he isn't one of our 14 best forwards and then we potentially have to pay him his full $750k to play in the AHL. That is a pretty low-risk worst-case-scenario.
These types of moves aren't splashy, but it is a good one. This is a negotiation that should leave both parties happy. And the Sanford trade gets better. I wasn't wild about qualifying and signing Sanford because I thought that it would be a waste of cap space. Army then turned that in to (now 2 years of) a younger league minimum player with upside. Fantastic.