What are the rules about distributing this?
There are no rules :) You can do whatever you like with it.
BTW, where's the source code of that release of FFT? I don't see the source available on the author's page. (I am blind, right?)
The main reason I did not post the source is because it is not yet unified or easy to compile, and I wanted to make the externals available before however many months it might take for me to get the code in shape. However you are welcome to get the code over here (but you have to figure out how to compile it):
http://eamusic.dartmouth.edu/~eric/MAX/FFTease/code.html
link error 0 dyld: pd multiple definitions of symbol _bitrv2 /usr/local/lib/pd/morphine~.pd_darwin definition of _bitrv2 /usr/local/lib/pd/pvwarp~.pd_darwin definition of _bitrv2
I encountered that problem a long time ago; the externals make calls to another library and earlier versions of Pd had a problem with this. I cannot however reproduce this problem on my current versions of Pd (0.38-3 and 0.38.4-extended-RC6). If more people encounter this conflict please let me know.
But it would be quite nice to be able to distribute FFTease built-in to Pd-extended.
I'm happy for you to do so, but only if you are comfortable with the way the software has been released.
the homepage states (in red!): "FFTease may be used freely for any artistic or research purpose." which i consider to be _not_ compatible with the GPL.
I think this is probably correct; as I understand it, the GPL places some restrictions on what you can do with the code. I think we are a bit more permissive, but if there is some way that you find our "licencette" more restrictive, I'm willing to consider relaxing it.
Eric