I had given up to try the iSight camera - and bought an Acan scanner on ebay from China. And it works like a charm, all scans with the first try. And 21 Euro is a good price for a scanner, I think, with no shipping costs. Only delivery time was 4 weeks to Europe.
And even if the iSight will work, I don't like to hold the book or the DVD somewhere up in the air.
I won't change anymore.