Let's see...
From the bots in F3d's post, plus the one in the OP, two of them have been around for five hours, one has been around for two hours, and one has been around for one hour.
Seeing that they each upload one video a minute, this means they have uploaded 680 videos so far, within five hours total.
Given that there are probably hundreds more bots than this, let's take a random guess at how many spam accounts there are on youtube. I'll guess 1,250. Let's divide that by 4. 312.5, but we're going to round up to 313 for easy maths. So, that's, from a random guess(that probably isn't even close to active bots there are on youtube), 616 five hour bots, 313 two hour bots, and 313 one hour bots.
4019 hours spent, total, by 1,250 bots. That's about 241 thousand videos, in five hours total. This isn't even close to the sheer number of bots there are on youtube, so it probably racks up some very, very large numbers.