We analyzed 1.3 million YouTube videos to better understand how YouTube’s search engine works. Specifically, we looked at the correlation between ranking factors — like views, comments and shares — with YouTube rankings. We learned a lot about YouTube SEO. And I’m sure you will too. Here is a Summary of What We Discovered: 1. Comments appear to be an influential ranking factor. We found that a video’s comment count strongly correlates with higher rankings. 2. Longer videos significantly outperform shorter videos. The average length of a first page YouTube video is 14 minutes, 50 seconds. 3. We discovered that video views have a significant correlation with rankings. 4. The number of shares a video generates is strongly tied to first page YouTube rankings. 5. There’s a moderate correlation between a channel’s subscriber size and rankings. This means that even small channels have a chance to rank their videos in YouTube. 6. Video likes are significantly correlated with higher rankings. 7. “Subscriptions driven” has reasonably strong correlation with rankings. Therefore, videos that result in new subscribers have an advantage in YouTube search. 8. We found a very small relationship between keyword-rich video tags and rankings. This could represent the fact that YouTube can now understand video content without the help of metadata. 9. Videos that contain an exact match keyword in their video title appear to have a slight edge over videos that don’t. This means that including a keyword in your title may improve your rankings by a slim margin. 10. We found zero correlation between keyword-optimized video descriptions and rankings. 11. HD videos dominate YouTube’s search results. 68.2% of videos on the first page of YouTube are in HD. I have detailed data and information of our findings below.