Here are some key factors that YouTube uses in its algorithm for search rankings on video:
- Relevance to the keywords/phrases entered in the queries. (Specifically, are there exact matches to the keywords/phrases in the title, description and/or tagging of the video).
- User Engagement (This factors in user activity on the video, including number of comments, likes and/or favorites. Higher engagement = higher relevancy)
- Trust and Authority of the Video Owner (This is something you can only build up over time, but as you continue to increase your channel subscriber count and overall channel views -- you will have an automatic boost in the search engine rankings for your uploaded videos).