I understand it as we wouldn’t actually see what he is watching, it’s all implied. In fact, if done right, the hypothetical viewer has no idea what Anakin’s status is, so it’s kind of like a mystery, like what did Obi-Wan see in the recordings that is so horrific?
Well, really, it’s either Anakin turns to the dark side, or Anakin is killed. Then, in ANH, Obi-Wan says he got killed, and in Empire, the viewer finds out that he lied.