The man ways Videos accrue (get huge viewer numbers). Notes from a presentation by Kevin Allocca of YouTube.
The video gets embedded in many places. Optimize your video for embedding, including multiple resolutions and sizes.
2. Searches on You Tube.
YouTube is the second largest search engine in the world. Optimize your video for search. Properly identify your video and select keywords.
People share video on all social media platforms. When you script a video, think about how to make it easy to share.
People click on the "related" videos on the side of the screen as they surf YouTube videos. Keywords you choose are hugely important for this.
If someone with a large number of subscribers feature your video, you get strong exposure.
To get an idea of how important this is, consider that Ray William Johnson has had more than a billion views! He puts up a lot of videos, and he works hard to promote his channel.
6. Paid Promotion
Straight up promotion where you buy search placement for your video.