Don't go blindly throwing money at random YouTubers, but yes if you can find social media influencers who aren't morons like these two then it's probably more effective than ad placement.

There's quite a lot of conflicting reports about the effectiveness of influencers. It really does depend on the campaign/product - I think a lot of companies are going to get burned by throwing cash down that well as they do with the advent of any new channel.

I don't know, don't you think that the population of morons in the pool of social media influencers is disproportionately high?

It depends.

I watch plenty of maker/electronic/mechanic channels on YouTube and having them recommend a product to me would definitely be more effective than putting an ad on social media or between videos.

Influencers like SmarterEveryday or SameerReviewsRunningShoes