The small customer base you can support doesn't seem to warrant a sales person, but there are many other ways to start building your client list.
You kind of need to know where to find your first clients, as a part of validating that your services are needed. Who are your ideal clients? Who needs your service badly enough to want to pay for it? Can you phrase the problem you are solving into a searchable term? If you can, why not try Google AdWords (you can start with some free money Google typically offers new customers). If you don't have a web site, you need at least a landing page (you can put one on a Wordpress platform or use LaunchRock and have an email collection module) that describes your services, benefits, and has your contact information.
Once you find your first few clients, you could offer a referral fee to current clients. Collect email addresses, by offering some free sample content (tips on your area of expertise) on your landing page, and send emails with the promised free content along with special pricing offers for your services.
You can also try to offer your services through sites like Odesk, Elance, etc.
Commission only and just 25%-50%? It will be a tough sell for you (pun intended) since the average cost of those videos is usually low.
By not having a small base salary, you have compounded the risk for a sales person several fold.
I would suggest giving several sales people a 2-3 week trial and then keeping the ones that brought in sales.
Your case would have been easier if it was a digital product. Since your cost of duplicating an existing thing (or give an account for a SaaS product) is next to nothing. You could then easily offer someone even 80% - 100% as commission.
But since you are a service based business, you have to make sense of all this based on the number of hours it takes you to create a video. If it's fairly automated for you to create them, go with a higher commission and try it out.
Finding sales people is just like recruiting for any other role: post ads on jobs sites or craigslist, find someone in your network on Linkedin, etc.