The videos uploaded here are all links to external sites. It's possible it was deactivated, as Mighty said, because the link no longer existed. Check the original site where you uploaded the videos and see if they are still on.

Everything is kept, so the only reason why they would be missing is because you or a mod deactivated them (deactivated content shows up in your sending options, and explains why they've been deactivated). I know back in 2010, when I was a mod, I went through the videos section and removed all of the videos that lead to dead links.

I can't back this up as a fact, but seeing as you've been here since 2006, it's possible that changes to the site, over time, messed with the galleries. Again, it's just a thought (because AS is notorious for bugs), but the likely case is they were removed over time. It's also possible that you had them uploaded to a site that no longer supports the video. I can't recall the site's name, but I know there was a site like YouTube that closed in 2006 or 2007.