Udf to ngr want to get back to udf

I am using a dvd camcorder (mini DVD disc) and Nero 6. I burned all my home movies to the mini disc (RW) and copied them to nero 6 on my hard drive. Nero put them in an image file .nrg Nero Disk image. When I go to burn it on a DVD it doesn’t have the right format to burn. Is there a way to convert the file to a burnable format. The original mini DVD was in .udf and it would work but I have overwritten the DVDrw disc many times and only have the .nrg files on my hard drive. Any ideas would be much appreciated.