How can I change a 1080 60I video shot on a panasonic HVX 200 HD camera down to 400 by 225?

Hmm… sounds like you need a decent transcoder, and the first one that comes to mind that is easy to use is HandBrake

Technically, you can use Compressor™ to do it, but Apple has made doing so an uncharacteristically obtuse and arcane process; enough so that even reading the manual didn’t help. For a company that people worship for their ease of use, they sure dropped the ball on this one :p That is why I am suggesting Handbrake. (Personally, I use SUPER but that is Windows-only while HandBrake is cross-platform.)

Tell me, what is the file format of the 1080i original video? I am not familiar with that camcorder, and sometimes they use something proprietary or just odd.