as an alternative, you can use the kml export
export the kml (every 10th point)
ps plot('v-do', -1)
load ps plot v-do ph disp
ps gescatter('project velo.kml', ph disp, 10, 0.4)
Convert the kml to a shapefile
ogr2ogr velocity_clip_large.shp .\export_velocity.kml
Extract the velocity from the attribute table (QGIS statement)
to_real( replace(substr(descriptio, strpos( descriptio,'Value: ')+7,4),'<',''))