I was watching that and was just confused. I just kept waiting for Brazil to be Brazil and it didn't happen.
Brazil cries foul - the night before their match with Great Britain, Brazil's team bus had mechanical problems and stranded the team on the side of the highway from Cardiff to London for 5 hours! News article by Martin Rogers on YahooSports.
I dont think they did it on purpose to be honest, just very badly organised. And it did surely help team GB a bit.
Oddly I can't find all those brazilian press reports blaming the loss on the incident, in fact I found this one http://glo.bo/NjCqER in which Barcellos says it had nothing to do with the loss. Maybe the british Mr. Rogers should stick to british reporting.