All good stuff. If I may add my own two cents here too to what the guys have said,if you are getting started and have 20 dollars and perhaps a CPA account or even clickbank, maybe use this method. I have been using this particular slant on video marketing now for around four years as a part of my overall business model. I have found it a method that works very well for me. Its a bit long winded so I will summarise as best I can in this space.
I find offers from my CPAs, any niche will do really. I then find videos related to my product where the owner has a certain amount of views but has no link to anything. I then contact the owner and based on a spreadsheet calculation I use, which is based on several variables, view count, time up, conversion rate for typical youtube videos, which is less than 1% in most instances, I calculate how much I could earn from traffic off this video. I then contact the owner, again I have a very particular template I use for this mail and I offer then a certain amount per month, to, in effect, rent their video. Now there is a high rate of ignoring on their parts, which is to be expected, but a certain % will take the offer. I have rented videos in the past for $20 per month whilst making 400 - 500 off that video. The reality is that some owners don't realise the value of the traffic they have and have never thought of monitizing it in any fashion. Given the sheer volume of videos on youtube etc there is always someone who will be open to this approach. This has been a consistent source of traffic and earnings for me for years now. Again, I never, never offer to buy their accounts, just to rent their vids. Hope this helps and if you have any specific questions, which you may, let me know and I will post them up