User blog comment:AeroAttorney/THE BLUE BOX./@comment-1729807-20110109111532

The blue box is the video loader for the wormhole / light-tunnel sequence which plays when you load into the map via fast-travel. You spawn in that room at the beginning of the load-in, the video plays, then you are moved to the New-U station - this is why players in an online room will see new entrants spawn at an arbitrary place in the map before the character comes into view: that arbitrary place is the "blue box".