You can add you link to the description box of the video AND make it live/clickable by putting it in the
http://www.etc-etc-etc.com format.
If you're doing Clickbank stuff, it's BEST to use your own domain and forward visitors to the product. At the very least you need a Blogspot URL you can forward with, a TinyURL link, or a .info domain name.
The best way to go is to buy a domain name that is similar to the product you are promoting. One trick I've used is mis-spellings. Hyphens are good too, if you can get them.
So if the name of the Clickbank product is -
www.BuyThisEbook.com - you could register
www.Buy-This-Ebook.com or a mis-spelling like
www.BuyThisEbookk.com
Hardly anyone will notice that extra letter at the end, and it's likely that YouTube's use of the "MORE" tag/button in the description box won't even make it viewable unless someone clicks "More".
If you're low on cash, one more thing you can do is to use subdomains. This way you can save money and just run everything off one domain. Your sub-domain would look like
www.BuyThisEbook.MyFrickinWebsite.com. Again, with the "More" button in the box only those who click "More" will see the full link.
Plus most of the douches that use YouTube hardly pay attention anyway. Some just click, click, click on stuff.
There are some other things you can do, but I don't feel like spilling everything here just so some turd can copy it all into an ebook. No thanks.
I'll say this - the best way to learn is to search around YouTube and see what other people are doing. But don't just blindly follow, because 90% or so of the guys on YouTube who THINK they know what they're doing are actually doing some of the simple, basic shit wrong.
Once you find that rare 10% dude who knows what he's doing, you'll learn a ton.
If you have any other questions just ask. I'll answer, I just don't want to fucking ramble on and on and on. It's a bad habit of mine. back to work.