Hello, I have a funny home video posted on Google Video and I was
emailed by a major ad agency in San Francisco asking for permission to
use the video and a release form attached.   During my email exchanges
with this representative of the ad company, with a job title of "art
buyer", she seemed to be very hesitant and broad on providing details
for the video's use and the possibility of compensation was not
suggested (only until I told her in later emails that I wouldn't do it
for any other reason).   Some answers to my inquiry on the subject of
my video's use involved phrases such "viral advertising campaign",
"clip will be used for Yahoo! Videos" and "They will run the add for
three months on banners online and a video screen sandwich board".  
Discussion of compensation only came up when I mentioned my general
motivation for releasing the video to them.   In reply to this subject
I was offered an amount under $300.00.

In conclusion I have no experience in this industry and have no idea
how to monetize the value of my video and to properly negotiate with
this ad agency.

I  am looking for advise on the best course of action for my situation.   

If the course of action is to contact an intermediary of sorts to
negotiate then please suggest the most appropriate two or three for my
case.

Thank you