This keeps a playlist of what you liked and uses that to recommend videos, allowing you to personalize and filter down the videos to only what you are interested in.

Example: Searching for "haskell" will give you videos about people named haskell as well as the programming language. After adding a few example videos to your list, you will get only results related to the programming language. The idea is to start to combat the incredible amount of noise in search results: believe it or not, not everyone enjoys rick rolls and gophers.