What editorial? Co-founder mythology is the title of the clip.

Are you referring to the part about singles watching the video? It's a recommendation. Doesn't favour either side of the debate.

"Single founders need to see this" is unwanted editorializing, especially the emotional-heightening 'need' word.

The mere fact that it's been submitted (or upvoted) is a recommendation to view. If it has special relevance for single founders, that can be included matter-of-factly: "The Co-Founder Mythology - a defense of single founders".

(And to further quibble: it's not self-confident single founders who 'need' to see this -- they already know cofounder risks! It's those who are biased against single-founder startups.)