pliers: extractors fail

I am having problem getting the extractors from the second README example to work. here is the code to recreate:

from pliers.stimuli import VideoStim
from pliers.extractors import (STFTAudioExtractor, PredefinedDictionaryExtractor, ComplexTextExtractor, ClarifaiAPIExtractor, IndicoAPITextExtractor)
from pliers.filters import FrameSamplingFilter
from pliers.graph import Graph
clips = ['../pliers/pliers/tests/data/video/obama_speech.mp4']
clips = [VideoStim(f) for f in clips]
#nodes=[PredefinedDictionaryExtractor(['subtlexusfrequency/Lg10WF'])]
nodes=[IndicoAPITextExtractor(models=['sentiment'])]
g = Graph(nodes)
result = g.run(clips)

using either of those nodes, I get an HTTPError: HTTP Error 401: Not Authorized. The earlier nodes in the example work fine so it’s not a general problem with my setup.