There are some critical factors in on-page SEO for Youtube videos, but it’s very simple to follow.
First, when you created your video, name the file exactly like you would your title to appear, with the main keyword in it.
Then upload the video file to YouTube.
Now, as I said, the title of your video should contain the main keyword and a few secondary keywords. In SEO, the title is the most important place to focus on, the following by description and as for last the tags.
Write a nice and long description for the video, with the main focused keyword at the beginning of the article. Don’t worry about the keyword density and stuff like that, just have the article focused on the topic that the video is about.
If you have a link that you want people to go to after they watch the video, put it in the description too, preferably on the first, second, or the third line of the description box.
The last is the tags box, just enter your main keywords and phrases, 3 – 6 is enough, don’t overdo it.
Publish the video and move onto the next step which is Off-page SEO.