It could indeed be used as "reason to believe" that the BC would produce "proof" that could be used in court.
When a police officer files an affidavit for a search or arrest warrant, she doesn't have to prove that the information sought is present, or that a crime has been committed. Just demonstrate that there is "reasonable cause to believe" that the evidence sought will be present and/or that a crime had been committed.
Well of course.
However, I do not believe a judge would grant a search warrant to an officer who stated in an affidavit "I read on an Internet blog that some guy claims to have a video tape of a woman who claims to be Obama's grandfather's third wife while claiming she was at Obama's birth in Kenya."