I find that as long as it does not repeat,or block content, move main content, it would be ok.
even a quck glow.
I dont believe that you can change peoples minds much, you can only suggest. If they are not interested, the the hard sell will only anger.
Internet customers are like rabbits approching food, anything suss or the slightest wrong move, and they are out of there.
After all your compedtors are only a few clicks away
What I rerally hate are these walk on videos
http://www.mediastreams.ca/servicepackages/custom_walkon_video.htm
a lot fast moeny SEO's have them