Agreeing with most responders here, Konami seems to be generally okay with fangames as long as they do not make profit from their ideas. However, I'm fairly sure of a few instances, although I'm not sure if it was Konami, that eventually shut down some fangames because of the bad rep they were getting as an indirect result. Something of the like of the fangame outdoing the original.
Personally I can say with CvBla, there aren't many restrictions that I know of, just the fact that we can't make money in any way, including monetization of youtube videos, or paid advertising by some other means.