I tried yours and its allowing me to walk into the portal on a lower lvl and then it sends this msg after I enter the portal on the low lvl.
data/movements/scripts/bglvltp.lua
nStepIn
data/movements/scripts/bglvltp.lua:9: attempt to index global 'player' (a nil value)
stack traceback:
[C]: in function '__index'
data/movements/scripts/bglvltp.lua:9: in function <data/movements/scripts/bglvltp.lua:1>