My youtube video down loader wont work!?

when i try to convert a video in a .wmv file it fails saying that it was caused by a not supported combination of parameters or by a not supported video codec. it gave me the link to get the codec file, so i downloaded it and installed it, and it still cant convert the .flv file into a wma file, and how the heck do i find the supported combination of parameters whatever that means please help!!!!!!!!!!!