I have a horrible feeling this has been posted on RI already.
It follows on from the excellent "Ludicrous Diversion". The new film goes a bit further and hypothesises how the bombings might have been carried out. Most frightening of all is the report of three of the hijckers being shot dead at Canary Wharf, shortly after the bombs went off. The hypothesis is the hijackers did not get on the trains.
Well worth watching.
Link to Google Video