Only creative works can be copyrighted - names, dates, places, can not be- no matter if it is one or one hundred billion. The fonts used, the arrangement of data- yes- those can be copyrighted but actual facts are not creative works and thus are exempt. Check the Copyright message board.
I'm not trying to "help" their case- they need none. Ancestry has a perfect legal right to use any publicly available process that any other search engine uses-period.
Exactly which section of the Terms and Conditions are you talking about?
What actual data you put up on a website is, other than creative intellectual work, there for anybody's taking.
There is a saying over on the Member Trees Message Board...
"If you don't want it copied then don't put it on the web."
This is particularly true of information that can't be copyrighted to begin with.