The sfw porn idea is really heavily saturated now, I tried doing that about 6-12 months ago and it was difficult to earn $20/day, mostly because so many people flag videos and YT just take them down. But you can apply this to thousands of other niches if you think a little wisely (ones to avoid due to saturation are sfw porn style videos, music & movies, humour and exercise niches - they all make money but you can bank seriously higher with much smaller and much more specific niches!). One I did a year ago was posting cracks of SEO tools, and my channel got pretty big with nigh on no maintenance; it was one of the very few methods of mine that were (and ever have been) running on autopilot, making ~$200/day. But I let that go for a better niche, which is earning me much much more
Just to give everybody a pointer in the right direction for the kind of niches you want, I would suggest that they revolve around something where products/signups total over $25 per (ie the AFF one shown here) and that there are no/less than 1 video result for that KW in Google (search for "Drake Shot For Me" or any music video for ex of a Google video result), and experiment with 5 videos per niche.
If those 5 videos average more than $20/day, get into that niche, and pile in more videos. Remember that the videos will accumulate hits and popularity over time, so it's not unusual that I have 50 videos per niche earning $200-500/day. Also, YouTube videos seem to climb into the Google video results reallllyyyy quickly if you XRumer blast them - Fiverr will sell you such services if you want to outsource.
If you want some good XRumer outsourcers, I use this guy cause of fast turnaround -
http://fiverr.com/portron/create-5250-verified-backlinks-using-xrumer or this guy if I want the quantity -
http://fiverr.com/xrumer_pro/create...cklinks-from-unique-domains-and-ill-ping-all; each gig I spread over 3 videos (so each blast is shared amongst 3 videos) and that's usually enoguh after a week to get me the Google video result spot.
YouTube's great because I can do all of this, and earn so much so easily, and I've employed two close mates from my college (make sure you choose who you employ wisely if they're your friends, some might try (and some have tried with me) to take advantage of your friendship to do less work), so I literally spend no more than 1 hour/day just managing whichever one of my two mates that's working that day. After their pay it still averages as a $300/day thing, so $300 for an hour's work. Not bad!
Good luck!
PS: Lately, my newest niche is banking me $200/day on top of this, with only 30 videos currently. So it's important that even after you're banking well you keep versatile, these gold mines I reckon are everywhere! Also, please no PMs/offers of money for my method, I'll ignore them, thanks