How much money do video game publishers and developers spend on
recruitment efforts in a year?  Meaning if someone were to offer a
product or service targeting video game makers that would aid or
replace recruiting of new hires how large is that market?

I worked as a games developer for a while, and as far as I'm aware
publishers and devcos spend virtually nothing on recruitment with the
exception of recruitment agents and the larger companies occassionally
advertising in the back magazines like Edge (see here:
http://www.edge-online.co.uk/archives/recruitment/index.php).

The reason is that supply vastly outstips demand; there are literally
hoards of people begging to get into the Games industry, and if you
have people constantly beating your door down for a job, then there's
no need for a heavy recruitment budget.