Stanley, There's a good conversation to have on advertising. I've been partnering with authors and specific guests that I have on my show. My basic pitch is, send me $100 and I'll create an ad, based on the episode that we do. When I create the ad, I use my YouTube link. I usually run the ad for 4-6 days...currently I run the ads on Facebook, but I've also had success on Bing. BTW the guests are trying to solve the discoverability problem too...so they are willing, and often excited to invest 100 dollars to collaborate on an ad-actually they prefer it over being asked to share the episode. Once that ad runs...that video ALWAYS outperforms whatever SEO/TAGs strategy I employ. Another aspect of what helps is the targeting available on FB.
I wouldn't suggest that an ad campaign is an inferior product-ads can work and are worth our time. It's not a free ride, but I can attest...a good YouTube strategy through TubeBuddy will absolutely elevate the floor of what the show does...but the ads amplify both the floor and peaks for an episode.