1) The building had been weakened in the initial attack/collapse, and it was clear that it would collapse eventually. The BBC had all the reports prepared for when the building finally did collapse, so they could talk about it right away. The early reading of the report was accidental, much like when obituaries for celebrities who are still alive are mistakenly published (as they have them ready so they can report on it as soon as possible).

2) That's BBC, a British channel, not American, so it's not that odd that they didn't realize the building was still standing there.

I see no evidence of anything more than that in the clip you linked.