You should *really* buy a few similar devices and do a basic teardown of them and spend some more time getting familiar with exactly what you want.
I know you don't want to hear the "you're out of your league" comments, but I've seen variations of this same situation end badly lots of times. In order to find and hire and manage the right person you at least need to have a functional understanding of what is practical and a solid concept of what the project should cost, etc.
Without the above you run an insanely high risk of hiring someone who is either vastly unqualified (though they would lead you to believe they can pull it off), or you'll find someone who IS qualified but ends up resenting that they are doing all the work while you are bumbling through making this happen.
I would suggest starting with this:
1) Put aside the whole form-factor part right now because you're going to be developing the first rev on a common PC base because that is the cheapest and most readily available platform to get started on. Once you have a functioning prototype you can determine resource needs and find the right hardware and port your project to that platform.
2) Write out a list of all the core features/functions you want. This is the product requirements doc (PRD), it should be formatted logically and cover all the core functions (finding cameras on the network, connecting to cameras, configuring cameras, streaming/recording video, displaying live video, accessing recorded video). Sometimes it helps to write a marketing spec sheet first and work backwards from there. Design the product brochure that highlights your compelling features and work backwards to what things need to exist in the product to make that brochure "real"
3) Throw a dart and pick a linux distro, it doesn't really matter yet but I'd probably use a standard Debian platform. Take your PRD and break it down to the most simplistic functions. For now throw away things like "play back video at 5x speed" or "video should be accessible with any browser or mobile device". This will look something like "Add camera by IP address (no need for auto-discover yet), stream/record video until hard drive is full (we'll worry about overwriting oldest video later), view live video from 1 camera, access recorded video (this might be just from the user manually entering a date/time, no fancy sliders or thumbnails yet).
4) Take the above and put up a job on elance.com or similar "rent a hacker" site. List out your basic specs from #3 above as the job requirements "Create software packages to run on Debian that can do x, y, z". Make sure you also mention that all source code should be commented, package dependenices clearly listed, and so on. Search for some other elance jobs and read them to get an idea of what to ask for.
5) Take the top 3 responses and hire each of them idependantly. You'll probably end up paying somewhere around $1000-$2500 in total for this.
6) Evaluate what you get back. At this point, if you haven't already, you'll start to realize how poorly defined your spec is/was and how hard it is to effectively manage programmers. I don't mean this as a jab at all. Here you'll have (hopefully) 3 semi-working variants of what you asked for. You'll start to see where you could have made things more clear, you'll see how different people implemented the same thing in unqiue ways and you'll hopefully get some ideas about which options seem most efficient, etc.
You're not going to go from zero to product on something like this without a lot of interim steps, and a lot of time and money invested. At this stage you're at the "you don't know what you don't know" phase and the best way to get over that is to not worry about all the minor things and just dive in and start tinkering. You're probably 6 months at least from really being able to hire the "right" person, so don't worry about using some contractors for now as essentially day laborers to start putting some of your ideas into motion.
After you've got a better grip on things, I'd personally start looking for a UI/UX person before I was hiring a fulltime programmer. The under-the-hood development part of this is pretty straight-forward, you're not inventing much there, you're just tying a lot of known concepts together. Yes, not just any person can do this, but you don't need a super-niche person either. What's going to make or break a product like this, IMO, is the user interface. Once you decide what it should/shouldn't do, you need to think about how you elegantly present all those options to the user in a clean and intuitive interface. I will tell you from experience that 99% of programmers will completely suck at this, and if you don't design the UI/UX up front you're going to end up with something that technically works, but in a very messy manner.