Algorithm and parameters for selecting recommendations for Netflix and YouTube videos?

Question

YouTube

Parameters for example:

1. floor
   
2. age
   
3. the country
   
4. city
   
5. likes
   
6. dislikes
   
7. last viewed
   
8. added to favorites
   
9. viewing duration
   
10. tags
    
11. categories
    
12. take into account what friends and people like you are watching according to certain criteria in your area
    

Of the algorithms, for example, sum up all the parameters, they have different weight coefficients, and at the end receive a kind of ELO, like in a tinder.

As far as I know, if there is a patent for an algorithm, it is most likely in an open registry, like a panda for Google search.

1. What can you say about Netflix and YouTube?
   
2. How do they select, filter and build recommendations?
   
3. What settings?
   
4. What are the formulas?
   

UPD 1 - habr

Answer 1

https://www.quora.com/How-does-the-Netflix-movie-r... the person from Netflix himself answers.