a bit of background before my question:
I've built a video sharing website that is specific to extreme sports, where users currently embed videos from third-party websites like Vimeo or Youtube. Really, the site is a blog that many users contribute to. I'm already live with a Beta, and will come out of Beta within the next few weeks. There is a strong likelyhood that I will soon obtain a bit of entrepreneurship funding from my government (a loan), and I believe that I have a solid plan for using this money to quickly scale the business. A key thing to note about the industry:
Many of my competitors are large extreme sports blogs that host their own videos, and do not use vimeo or Youtube. Among these competitors many provide an API which, if integrated, would allow my users to add their extreme sports videos to my website as easily as a video from youtube or vimeo. These are very high quality action sports videos, and would be of great benefit to my community. In some ways this could be beneficial to my competitors, all of which run pre-roll advertising on embedded videos (i.e. they will make money by me having these videos on my website). On the other hand, my website directly competes with their recent investments in user-generated content / social networking.
Embedding my competitor's videos in my website will undoubtably tip them off to my existence, I strongly believe that I have implemented user-generated content / social networking better than my competitors. My competitors have the means to relatively quickly integrate my implementation into their own websites.
And the question is, should I be worried about tipping off my competitors to my existence before I've had a chance to get my foot in the industry, build my brand, and at least to some extent scale my business?
Its always a consideration and a worry but in general new startups worry about this a little too much.
"They" have a few hurdles to overcome ... they
More likely senarios include
Looking at your business:
You need to get content from somewhere, unless you have an established core of people submitting or you have a deal with the likes of Warren Miller your best bet is to make a margin on their content and slowly reduce it as a percentage of the content on your site over time ... so far this is a necessary evil from your point of view.
If your idea is a simple UI change or a reformatting of the same data, then your in trouble, possibly rethink the strategy or drop it as "good but too easy to rip off" and save your time for the next good idea.
Most likely they have google alerts set on all relevant keywords, so they will know about your existence anyway, without you using their API. Robin's answer covers all the rest.. If there is quality content, use it.