Web spots increased the viewer attention rate by 53%, awareness by 52%, consideration by 27% and favorability by 26%. Prompted recall of brand advertising was four times higher for Web viewers.
68% of the online viewers retained information from the ad breaks, as opposed to 59% of the offline viewers. Analysts cite various reasons, not the least of which is the tendency to get up and walk away during TV commercials.
So, while you certainly can work very hard to create awesome web-only content, realize that your already successful (and expensive) TV ads might work even better online.