When a political commercial is funded by private organizations - including the DNC - it is required for the source to be clearly stated at at some time during the commercial. We've all seen them. "Paid for by mindless drones with no concept of reality. MDNCR.org"
There is no such advisory at the end of the commercials I have seen. Since you admit they only "appear" to be privately funded commercials, I'd say you haven't seen the required advisory either. So either they are breaking the law about private political organizations paying for ads, or the commercial is NOT being paid by private funds. Take your pick.