Interesting, that's just a fraction of the size of the digikey building, so obviously a lot more goes on.
But as you say, that area is hand picked.
Containers come in on conveyer where they are remove, filled with ordered items and placed back on the conveyer.
The container color maybe to signify if an order is now finished in that area of the building.
The downward facing camera visible on the conveyer line probably detects when a new container has been added or an existing container removed. It also probably can tell from the color which containers are done with that area on the factory. So blue containers are looped around and around while red go to the next area which deals with other parts of the order.
And there's also quite a few smaller conveyers at 90deg to the main conveyer from the other side, perhaps a holding area, or the first stage in the whole order process where new containers join the main line.