Keep in mind that "free traffic" isn't free.
Good content takes time, thought, and money to produce. High quality video, eg, can be very expensive. There's also effort involved in the promotion of your content. So be prepared for ongoing effort.
What i am looking for is some sort of metric like assuming that the video gets 5 views a day and 20% of the people clicked through the link then i would need 20 videos to get me 20 visits a day.
I think you'd need to have comparable videos to make any sort of predictions. Why 5 views a day? Some videos might get 500 views a day, and some might get 5 views a year. I suggest you look at individual view statistics on YouTube for videos similar to what you're anticipating.
That won't give you click-throughs, though. I think your 20% click-through thoughts, either for articles or videos (and I know you're just tossing out a figure) are wildly optimistic. Use site-search on WebmasterWorld to find threads on click-through rates, and how expected traffic diverges wildly from predictions. You'll see that it's far from an exact science.
You also need to pick your subjects/keywords/market area wisely, to get a sense of whether topics and keyword combination are actually searched. Check out the Google AdWords External keyword tool for initial keyword suggestions. You'll need to read up as well on how that tool is best used... and perhaps check out other tools that are available.
Note that we don't discuss specific tools in this forum.