I take claims that Oprah has had footage of the interview removed from the internet with a big truckload of salt.
Plenty of media companies are very protective of their content - they want you to access it through their own distribution channel (the International Olympic Committee, for example, which is zealous in removing unauthorised footage from YouTube, where they have their own account), or so you have to come to them and pay of you want access to the footage.
There are plenty of extracts on YouTube, just not the full interview. Harpo could well be making sure that the full interviews is only accessible through them - that would be sensible guardianship of their intellectual property rights.