The cameras do not have any light source and if it is really dark then it will affect the video. But that's one benefit of using our service because our pro editors have software and expertise to enhance the footage and make it as good as possible.
If you look on our blog you can see a lot of examples of low light settings (especially on the dance floor) and what the final outcome is. Most of it was dark outlines of people before we worked our magic. Of course the cameras don't compare to a $5000 pro camera, but they don't come with a bright light in everyone's face either :)
You may want to consider renting one of our pro cameras for $300.
Don't forget you can also work in strategic uplighting during your wedding to help with this issue. Check out this blog post to find out more.
Also, make sure to check our Camera How to for the best tips and tricks on how to get the best video no matter what the lighting situation is!