The code comment says "genres, tags, studios, _person_, year?", but does no matching on common people between films. This PR augments similarity score treating people similar to tags.
builder.Append("+ (Select count(1) * 10 from ItemValues where ItemId=Guid and CleanValue in (select CleanValue from ItemValues where ItemId=@SimilarItemId))");
+ builder.Append("+ (Select count(1) * 10 from People where ItemId=Guid and Name in (select Name from People where ItemId=@SimilarItemId))");