Australian lawyer and one of the mods at /r/auslaw here. I can confirm that this story is very likely bullshit (as if you need to be a lawyer to see that though). If the tape was not discovered during the pre-trial discovery process, it would probably not have been allowed into evidence, especially after the defence and prosecution closed their cases. What MAY have happened (if this was real), is that the judge told the jury to leave, then the lawyers had an argument as to why the evidence should be admitted at that stage of the trial. If the judge said the tape could be admitted then it would have been played for the jury once they had set up the projection equipment. If the judge said it could not be admitted, then it would not be and OP might have been screwed. Though it's possible that the prosecution would have dropped the case, or a mistrial would have been declared and a new trial ordered.

Also, a BJ tape is evidence that she gave him a BJ, not evidence that he did not rape her before or after the tape was made. EDIT: actually, very good point dorino0net and flabbergasted_rhino - the tape would likely have captured the statement "I will tell them you raped me". But yeah, still a bs story.