The program depends on the user. Yeah, in theory, any program would do, even at a cost to edit frame by frame in Paint
BUT, better (often more complictaed) program can allow you to edit batter, faster and much more efficient. And this efficiency is the key. Yeah, simple programs like WMM or UVS will do, but it'll often take you 5 times longer to do a good edit compared to semi-pro programs like Adobe Premiere or Sony Vegas. I know that Premiere comes in a Pro edition aswell (I have one ). So, if you're experienced you won't go wrong with a semi-pro or pro edition of a program. And it wont take you long to get used to it. If you're new, stick to UVS or WMM until you get the feeling that you need something more powerfull.