Alright, I think it sounds like a bearing going or a slipping of a clutch type sound. Is there anything that uses a clutch or bearing in the driver section?
In all seriousness, pull the v-belts and fire up for a few. Sounds like an alternator to me. Make sure you have the muffs running water to the impeller so you don't cook that.
With sound still present and no belts on the motor, that leaves either the front end - timing chain or harmonic balancer rubbing, or back end flywheel housing. Take a couple foot long wooden dowel and hold it against your ear and different spots on the motor to assist in isolating where the noise is from.