Oh, I really like how the muggle artifact is much better able to distill their feelings than the Pensieve! In fact, it makes sense: the Pensieve helps one to become more objective about the situation viewed, while it appears the Viewmaster helps one to understand the subjective aspects--in short, one's feelings.
Severus' not knowing what he needed to do to help Harry emotionally, and the fact that Harry seemed unaccustomed to going to him for emotional support was so sad, particularly in terms of their accompanying lack of communication about their sexual desires. Though, it is wonderful that the Viewmaster helped to heal their relationship both emotionally and sexually.
Oh, yes, the spanking scene was wonderfully erotic....