Two problems. One is that freebase is returning a malformed charset: charset="utf-8" vs charset=utf-8 . The other would be apparent once we put out some code to be much more lenient in what we accept.
Due to some of the vagaries of how YQL is processed internally -- the way it normalizes data -- we unfortunately have to put an additional top level element into the result named 'json' for this case. So your itemPath will end up being 'json.result'. I'm sorry that this doesn't yet work because of our strict charset handling.