Dose any one recognize this noise

im not sure how to explian the noise but you'll know it when you hear it some times it become really loud and continue untill you shutoff the engine i can hear it while driveing during lower rpms (like turning) im not sure if its there or not at higher speeds, the noise is kinda random some times it wont start doing it at all then other times itll start just a few seconds after turning on the engine
if you would like to hear the noise go to http://briefcase.yahoo.com/[email protected] and click on the engine noise.avi file

recorded it with a dv video camera 1 to 2 feet from the engine (its pretty loud, i was kinda close at first but all i got was static so i moved back till it was normal) i just got around to checking it and as detaled as posible, for the moment neyway, it dosnt seem to becoming from any of the accessories or anywhere infront of the engine at that more of the engine itself as far as i can tell it sounds kinda like something metal vibrating or rattling....hum i wish i had a magic noise fixer

I have posted this on many forums noone seams to know what it is, maybe someone here knows?

sounds almost like the bearing on the accessory drive belt tensioner is going bad. that or maybe the fan clutch.