Links, lies and video clips

My interactions with a few clients recently made me realise that there are certain misconceptions about SEO. I realised that there are a lot of misconceptions out there with regards to Search Engine Optimisation (SEO).The two main concerns I would like to address here, are linking with free services and what makes video, particularly youtube, so popular with search engines.
 

Linking exchanges:

Making use of free linking may have a detrimental effect in future. Using linking affiliates with no or little original content on their sites tends to have great short term gains. My theory is that this is when the crawlers makes its first pass, only calculating the number of links to your site. As the search engine starts analysing the value of those links, which takes months, you may be placed in what is called a "bad neighbourhood." Once this has happened, getting your reputation up with the search engines can be a very difficult  situation.They tend not to list bad neighbourhood sites with premium key phrases (phrases which are used more often.)
 

Neighbourhoods:

The theory is that neighbourhoods are having a greater impact on the modern algorithms used by the top search engines. A neighbourhood with similar content is more likely to have good SERP. If you can create a content neighbourhood of related sites with related content, the search engines will notice you.

With SEO content is king. Content in the form of text. Text which the crawlers can read. Traffic to you site has an impact, but that traffic is not measured in bandwidth. I say this as I use to be under the impression that bandwidth has a big impact. Good thing my knowledge has grown on in the field. It turns out that the only area where bandwidth effects your reputation with a crawler is the speed with which your pages load.

But why do video sites get such good SERP (Search Engine Ranking, not to be confused with PageRank)? I think that often it is the comments on video sites that drive their SE reputation more than anything else. That and the amount of unique hits the video gets. Not the amount of bandwidth it takes to play the video.