Right now we don't have plans to charge for FlashBack Connect - its value to us is more in making it simple for FlashBack users to easily share videos, particularly if they have interactive elements that can't be handled by YouTube, etc.
We do have longer term plans to add simple editing and annotation features. If/when we start to charge for FlashBack Connect, we would aim to do it so that existing users are moved onto the free plan, and have the option of paying for more features or storage. In this way, you can use the service now without being concerned about suddenly facing charges in the future.