Only accurate when it is about to happen.
Not that accurate.
As I recall, Paul Ryan went from about 5% to 98% in a few hours before the Romney camp acknowledged his selection for VP. Intrade is worthless as a predictor until the very last few hours or perhaps days in the case of a Presidential election.
Right now the betters are looking at the headlines for a bunch of phony polls and believing what they read.
Suckers.