I know I will be writing a hub about SEO, probably a few. To answer some of the comments now though:
@Dave Mathews, asianlight: SEO is a way of optimizing your page, site, etc for better ranking with your target audience.
@prairieprincess: long-tail is simply the shape of the graph in response to hits. For example: Shoes is a keyword and Nike soccer shoes would long-tail. Long-tail is finding the niche and being more focused instead of so general.
@seeker7: using keywords is easy to fit in and keep the flow, density - if the article sounds good and doesn't sound too worked don't worry about it. Bold, italic, headings - use them to draw attention to keep words when appropriate. Lists there are times for them - take advantage of correct use when needed. And layout isn't a big deal, if you focus on quality most of these rules are covered anyways. Check out the flagship hubs rules. Good rules to go by.
@ClickrNet: the search systems decide you ranking. Search engines are just pretty much a gui. There is ranking for everything - videos included - it all revolves around the text (content) and backlinks etc. - btw I am jealous of the followers you have in such a short time.
@Wesman: it is possible, but would be very hard for clean data in some instances. they would have to look at time spent viewing etc. which can be thrown way off. If they change - people will figure out what to do.
@Fran: you can always use rejection slips as wallpaper.... forgot who did that irl.
@stuff4you: about the only thing you need to know about value of keywords is the competition. And that is only if you are looking at possible price your ads will pay you. Bidding, buying etc is if you are advertising. And if you want to learn about SEO, there is a lot of free information out there.
I hope that helped for now. I know I still experiment to learn more - one reason I am on hubpages.