I've been running YouTube ads for the past year and a half and I've seen 500%+ ROI on ads that haven't even been fully optimized.
YouTube has definitely been a game changer with generating traffic for us and I would recommend you to target business opportunity related channels that talk about digital marketing, ecom, self-improvement, affiliate marketing, and other similar niches. On top of that you could also target viewers of my YouTube channel (Adrian Gee) as they're already warm prospects.
The video ad below is currently our top performing ad and we're confident it will generate you sales.