I'm the owner of a web business, and think you're making a few pretty significant mistakes:
1. You shouldn't be looking for a custom solution. Especially not as a beginning entrepreneur. Think of it this way: if you go the custom-made route your site will always be in "beta" mode as there are no other sites using the same software (no benefit of community-based support).
A cheap script that probably does everything you're looking for can be found here (haven't used it, but colleagues have and they like it):
http://www.entertainmentscripts.com/social_features.php
2. Given your initial investment requirement and your financial situation, don't take on partners. The cost of drawing up the legal arrangements will be nearly as much as the investment itself. It seems like you're just looking for the advisement aspect of partnership as opposed to the capital contribution. There are many people out there (myself included) who would be willing to give you advice as you set up your business.
3. Work on developing your Unique Selling Proposition more. The "Youtube for X niche" model is overdone and destined to fail in my opinion. Without knowing your niche, you need to be thinking of ways to incorporate video as a part of an overall site that can be differentiated from the dozens of video-sharing sites. "We have lots of videos of independent movies" is not enough. "We are the only site where you can watch independent movies, and then listen to interviews with the directors and talk with other independent film buffs" is more along the right idea.
Hope that was helpful. I'd be happy to talk more if you want, just send me a PM.