It is impossible to prove the past existed, as all one's proofs can only inhabit the present, even when, as in the case of a video recording of this past, they naturally claim to be such proofs. One's proof is still, whatever it alleges, an element of the present.
This is perhaps much more serious than might appear. The past and future are merely and ultimately words existing within the present, and the only serious intellectual or spiritual concern is immersion within this present; for example, while engaged in a 'mundane' actvities being wholly apart of whatever it is one is doing rather than one's body somewhere and one's mind off rambling somewhere else. How such mundanities become real and interesting, and the category of mundane to which they had mistakenly been condemned resulting in the most far-reaching of essentialy schizophrenic results; life divided by a scattered mind.