Overhead shots of Tony and Swan ... was the apartment in the Astrodome?

I have not seen the interview, but I suspect what he meant is that filming from behind a fireplace would be just gimmicky and without a real motivation. From whose viewpoint are we supposed to be watching the scene - Santa Claus's viewpoint? What would Santa Claus have to do with the story and why should we the audience see the scene from his perspective?

However, filming from the ceiling, looking down upon the two conspiring weasels could be interpreted as watching from God's point of view; or from the viewpoint of reasonable, moral people who are (literally) "above" the slimy practices of the little criminal creatures (= Tony & Swann) who smugly but mistakenly think they have control over their situation. The overhead viewpoint makes the scene kinda ironic, it's like watching crawly insects doing their thing while we the audience already know that their plan will (of course) not be successful (because we trust the director to not let these criminals get away with whatever evil they're planning).

Another reason for the "viewpoint from above" may be that the audience gets a clear overview of the logistics of Tony's plan; it's rather a complex plan, and Hitchcock had to make sure that everyone in the audience (not just the smartest viewers) would be able to follow how the plan was supposed to go (before Hitchcock throws a wrench in the actual execution, of course!).

Just my two cents'.

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Joe Satriani - "Always With Me, Always With You"
http://youtu.be/VI57QHL6ge0