How to change type from one owner to two different types of owners I currently have (tables changed):

User

UserID uniqueidentifier,
CompanyID uniqueidentifier, (for future reference)
.. more unrelated fields

(PK: UserID)


UserRating

UserID uniqueidentifier,
MovieID uniqueidentifier,
RatingTypeID uniqueidentifier,
Rating tinyint

(PK: UserID, MovieID, RatingTypeID)


RatingType

RatingTypeID uniqueIdentifier,
Title varchar(25)

(PK: RatingTypeID)


The RatingType table contains "Favorite", "Need to Watch", etc.  So actual Rating value is how much they liked a Favorite, or how badly the want to watch a movie etc.  

Now I introduce a new table:

Company

 CompanyID uniqueidentifier,
 .. more unrelated fields


The idea is that if a user becomes part of a company, due to requirements that cannot change, all the Ratings need to be Company ratings and not User Ratings.  I'm not a normalization guru, but for some reason creating another table (below) seems redundant, but maybe I'm thinking to much into it.

CompanyRating

CompanyID uniqueidentifier,
MovieID uniqueidentifier,
RatingTypeID uniqueidentifier,
Rating tinyint

(PK: CompanyID, MovieID, RatingTypeID)


This feels incorrect because it almost matches the rating table and if I need to do any averages it becomes more difficult to average across two tables.  Is there a better design for my needs?
I have a feeling you will benefit if you borrow party concept from Party-Role-Relationship, one of universal data models, which is capable of keeping all information you needed. 

So you will have party_type table that will currently have 2 records, person and organization, one common party table that holds all people and companies (you may want to add 2 more tables , person and company that hold attributes specific to people and organizations respectively), and your rating will have a reference to party.