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Hey, I think there are a few things to look at when ranking a video on youtube. . . Comments Video Responses Likes & Shares Website Embeds Title & Description Amount Of Views/Duration They Watch The Video For Thats what I would look at anyway, hopefully someone else will give us their input too  

Link building is the way to increase your domain authority. Generally links to any part of your website will slowly push your DA up. So continue getting quality links and wait for the next few updates to see your DA go up. I wouldn't fuss it if your site doesn't have a high DA or links aren't being found. Google will most likely have them indexed anyway.

Link building is still the way to go, here is a good site with a lot of ideas: http://pointblankseo.com/link-building-strategies