What would scrolling:'no' do? My bet is that it will hide de scroll bars on Firefox, but the QR code will still be incomplete, won't it?
I understand your concern about the mouseover action, that was something Apple/TradeDoubler recommended us to do to increase app downloads by making it easier for people to scan the codes without having to click on the link first. I myself didn't like the idea first but decided to test it out. No complaints at all so far, and it's been like that for a few weeks. ;-)