It all comes back to permissions - it may seem like a nicety, but it really does matter. You can chop up a film, and the studios aren't going to notice or come after the TChris household; you're small potatoes. But a business based on doing this is going to get noticed.
Now you are implying that it is illegal for TChris to edit his own copy in his own home for his own use just that no one will notice if he does. Is it legal or is it not legal to edit one's own copy in one's own house for one's own personal use?