I didn't seem to have much trouble finding them in streams such as the one in the video which is at Lookout Bay, just a few minutes from the station, which were small, not fast running and with a canopy of draco. Streams such as Tucker stream going into Tucker Cove which is fast flowing, a lot wider and only tussock along the edges with no draco canopy, I didn't see any out in the open, but a net found them under the tussock edge.
I did three trips to Campbell when I worked for the MetService so had plenty of time to have a play down there.