John Barton, the distinguished British director and Shakespeare authority, produced a fascinating series of workshop sessions on "Playing Shakespeare" which are available on four DVDs. Here is an excerpt from the article on Barton in Wikipedia:
In 1982, while working with 21 [Royal Shakespeare Company] members, including Judi Dench, Ian McKellen, Patrick Stewart, Michael Pennington, David Suchet, Sinéad Cusack, Ben Kingsley, Roger Rees, Jane Lapotaire and Peggy Ashcroft, Barton recorded nine workshop sessions for London Weekend Television. These programs, together entitled Playing Shakespeare, were aired that year and became the source material for Barton’s best-selling book of the same name. Though stiff in his resolve against writing on the subject of performing the plays of William Shakespeare, the surprising success of his nine-part televised series convinced Barton of the desire, and of the requisite necessity, for this book. It, too, found great international success, and remains a most popular guide with working actors, (as well as those aspiring to be working actors), who study and train upon the works and words of The Bard of Avon. Playing Shakespeare, the ITV series, is now available on DVD.
One of the sessions was devoted to Barton's instructions on delivering soliloquies, including those in Hamlet. It was Barton's expressed conviction that all soliloquies should be delivered to somebody and should not be acted as if they were internal monologues of the character. In the many instances in which the actor is entirely alone on the stage, he should, according to Barton, address the soliloquy to the audience. Barton has some of the assembled actors and actresses demonstrate this method of soliloquizing, and it seems very convincing. The actors chosen to give demonstrations seem much more natural and comfortable when addressing the audience directly.
There are cases in Shakespeare in which Barton would say that the actor would not be addressing the audience in a soliloquy. An example would be King Lear's famous speech in Act 3, Scene 2, beginning with
Blow winds, and crack your cheeks!
Lear is not talking to himself but to the winds.
Another good example would be Antony's soliloquy in Act 3, Scene 1 of Julius Caesar, beginning with
O, pardon me, thou bleeding piece of earth,
That I am meek and gentle with these butchers!
Antony would be addressing the corpse of Caesar throughout this soliloquy.
The important point is that all soliloquies in Shakespeare, according to John Barton, were intended to be addressed either to the theater audience or to some person, dead or alive, or some thing, visible or invisible. This would include Hamlet's famous soliloquy beginning, "To be, or not to be: that is the question" (Act 3, Scene 1), and the soliloquy highlighted here which begins with "O, what a rogue and peasant slave am I!"
The four DVDs titled "Playing Shakespeare" are highly recommended. They are available on Netflix and probably at many public libraries. Some of the actors who participated will be very familiar--though much younger looking. David Suchet is best known for playing Hercule Poirot in the TV series. Patrick Stewart starred in a motion picture production of Macbeth. Ben Kingsley won an Academy Award for his starring role in the movie Gandhi (1982).