Maybe there's a bad ground.... maybe theres a broken alternator, maybe the batteries dead, maybe the battery connectors are rusty (highly doubt), even if they were rusty, power would get through the car.. maybe not as well but not to the point the basically dead. I personally think it might be a bad connection to the Ground, but that not up to me, thats up to the mechanic which I highly recommend she goes too!. Maybe the ground wire is barely holding the frame or not holding on at all. that might show power spikes, when you see 1:00, does dim? Or it could be the alternator, I dunno.