Could Explosives Have Been Planted Unnoticed in the WTC Buildings?

911Blogger.com posted an interesting article on the question of whether explosives could have been planted in the WTC buildings without anyone noticing.  The video was the most interesting part:

And for more detail:

Someone in the second video points out that if the New York newspapers hadn't been on strike, then they would have reported on it. Yes, perhaps if they had known about it. But there was local and national television that wasn't on strike at the time. Why didn't they say anything about it?