Sony and IP cameras generally (Score 1)

Before I sold out for law school, I worked with some DVR software from Sony that was actually pretty good. Unfortunately, I can't for the life of me remember the name. (Just found it - Sony RealShot) At the time, it was pre-release, but I think it was supposed to come out in late 2004. I'm sure it's Windows-only, but it didn't require a dedicated box, like a lot of the commercial DVR providers. So, at least you'd be able to handle OS security without having to battle the DVR app, too.

Of course, it being Sony, there's a good chance that it only works with Sony cameras. I only worked with their cameras at the time.

As for rolling your own... I wouldn't think it would be that hard, if you're willing to put some developer hours to it. Most of these IP cameras use the same HTTP-based mechanisms for sending data. I managed to get video off of a couple different cameras without too much trouble. I developed in .Net but I'm sure there are libraries to support this in whatever language you prefer.