That is curious. If you want to see video of the collapse, see here
http://www.wtc7.net/videos.html
It looks like a planned implosion, leading me to believe that the structural weakness was near the base of the building. The towers went down from the top down... not so with 7.
Odd, I will look more into this.
EDIT: Ok, I've looked more into this and its stupid too and doesn;t stand up to even a shallow analysis.
The accusation is that WTC 7 was demolished with explosives, as well as the towers, in conjunction with the airplane strikes. They make this argument using grainy footage of small explosions that appeared on the surface of the buildings as they came down, called "squibs".
This could make sense as a theory if it were not for the following:
1) When thousands of pounds of building is collapsing on itself, the sheer airpressure created is enough to blow out windows.
2) The amount of explosives needed is huge to do this. Are you telling me that the tens fo thousands of people wo worked in those building never founds any of the charges?
3) The tower collapses did not look like a professional demo job. Large chunks peeled off the sides and the area of debris was huge.
This is not to say that WTC 7 wasn't demo'd. It may have been, but at leasy that would make sense. It was on fire and had a lot of damage. If the government did demo the building, why didn't they explain it? That is another interesting story I'd like to know if it is true.