Well the good news is, after all that, the development server is now safely behind authentication and the level of traffic to the site has returned to previous levels for the last three weeks. Fingers crossed it won't be going anywhere.

It has been a wake-up call for the client though and it's started some useful discussions. Every cloud...

Thanks for the support!

I can still access the videos by going to the "2012 Mozcon Video Bundle" under the Learn SEO menu. If I scroll down I can see the "MozCon Seattle Seminar 2011" and 2010 videos.

Just tried clicking on a couple and they play ok. (Did notice that some of the avatars are missing though.)

If you can't see these you might want to contact support. help[at]seomoz.org

<object id="plugin0" style="position: absolute; z-index: 1000;" width="0" height="0" type="application/x-dgnria"><param name="tabId" value="ff-tab-1"> <param name="counter" value="165"></object>

The disavow tool isn't going to "fix" these 404s.

404's aren't always a bad thing. The warnings in GWT are just there to make you aware that there's potentially a problem with your site. It doesn't mean there IS a problem.

Is there content on your site that visitors clicking on these links should be arriving at? In which case you want to implement 301 redirects so that your visitors arrive on the most appropriate pate.

If there's nothing relevant on the site any more - a 404 error is perfectly acceptable.

Of course, you want to make sure that your 404 page gives the visitors the best chance/incentive to dig into the content on your site. Adding a nice obvious search box and/or links to most popular content may be a good idea. If you're getting lots of visitors from a particular site that you can maybe tailor your 404 message depending on the referrer.

The drawback here is that links pointing at 404 error pages won't pass link-equity. If there is value in the links, and you're happy that they're going to be seen a natural/authentic as far as google is concerned then you can always 301 redirect these.

Where you really should pay attention is where you have internal links on your site that are reporting 404s. These are under your control and you really don't want to give you visitors a poor experience with lots of broken links on your site.

How big is the site in question? How many pages are there to de-index?

What does Google Webmaster Tools tell you about the old domain? Does it show pages being removed from the index over time?

If you do a site:{old domain} query, can you see that the number of results being returned is gradually decreasing?

How have you implemented the redirects?

Have you submitted a change of address request in Webmaster Tools?

On the new website, have you submitted a sitemap fom the old website as well as the new one?

What does the backlink profile on the old domain look like? Can you start to get authoritative links to the old site updated? What about any embedded internal links in your content - have they also been updated?

More guidance from Google here:

Webmasters Tools Help: Move a site with URL changes

This means that your domain hasn't been crawled and that there's no data in Mozscape.

You get the following explanation from OpenSiteExplorer when you look for a domain that isn't crawled:

Although our index is large, there are a number of reasons why we may not have data for the page you've requested. These can include:

• Recency of Page Creation:
  Mozscape crawls the web constantly, but we update the index only once every 30-40 days. Thus, pages and links created since the last index update won't be available until we've seen them. A typical timeline for getting a page/site included in Mozscape is 45-60 days, sometimes less for very important or well-linked-to pages.
• Deep Down in the Web:
  Our crawl focuses on a breadth-first approach, and thus we nearly always have content from the homepage of websites, externally linked-to pages and pages higher up in a site's information hierarchy. However, deep pages that are buried beneath many layers of navigation are sometimes missed and it may be several index updates before we catch all of these.
• Blocked Pages:
  If our crawlers or data sources are blocked from reaching your URLs, they may not be included in our index (though links that points to those pages will still be available)
• No Links:
  The URLs seen by Mozscape must be linked-to by other documents on the web or our index will not include them.

We can see that your site has been indexed by google (site:autoproject.com.au/) so it seems that there's nothing to block crawlers from indexing your site.

If we look at MajesticSEO, we can't see any indexed links to your site either.

It looks like your website went live earlier this year (sometime in April?) but as yet hasn't managed to attract any links and it's those thinks that Moz will used to determine your Domain Authority.

In this case, look at your outreach and consider how you can get some good quality links from authoritative domains (in your niche).

I'd echo Tom's response. Allowing your content to reported does expose you to risk.

Chances are these outlets have much stronger sites. How much traffic is landing on your blog articles? Is there a likelihood that you might start competing against your own content in the SERPS?

I would look at the the publications concerned and try to understand what matters to their readership, what kind of demographic do they have and then rewrite you articles (or create new content) specifically targeted to their audience.

If you've got a nice library of old blog posts then it might be worth creating an ebook of the very best content and using that as a link building or lean-gen asset.

Add a benefit, make your titles compelling and give people a reason to click on them - don't make them harder to read!