Notice how %obj is never used?
Cause it's not supposed to be there. :)
Edit: Oh, cause he's using FxDTSBrick::onPlant, which is the physical object function, as compared to FxDTSBrickData::onPlant, which is the datablock function.
fxDTSBrick::onPlant(object ID)
fxDTSBrickData::onPlant(datablock ID, object ID)
BrickDatablockNameHere::onPlant(datablock ID, object ID)