There really isn't a way to submit spec commercials like there is for screenplays. Agencies and clients are a pretty tight knit group, and you would have to have a relationship with a creative director who would ask you to freelance and submit ideas. Clients, unfortunately, are rarely looking for general scripts, no matter how good. Rather, they are looking for very specific scripts that solve a business problem, which they brief agencies to help them with, who then create advertising campaigns in response. If you wanted to be considered for work, you would need to create a spec portfolio of scripts/ads, and then submit that portfolio to agencies and creative directors.

I've worked in advertising for quite awhile now, at agencies and on set, and I've never seen a script formatted like this. Maybe you would do this if you needed to create a shooting script, maybe. Google "the art of deck making" and click on the first link for a better example.