Define paid. I did not invest money, but I invest time. I visit a couple of forums on a regular basis, tweet a bit, post a bit on FB and do a video every now and then. YT drives about 10% of traffic to my website, so that's more than any add ever got me. Videos are simple screen recordings with captions + music from the free YT library. Takes an hour to 2 from recording to actual upload.
In my experience it's results are better than paid adds and all that. Years ago I did spent money on ad-sense, yes it got me visitors (some), not sales. I even advertised in real paper magazines, with coupons and all that, coupons were used zero times.