Try to burn .mpg for VCD, Nero wants to 'encode' it?

Hi. I am trying to burn a VCD file .mpg with Nero Express, v…
I have had this problem on and off for a while now,
some vcd .mpg analyse just fine and burn, and then some need ‘encoding’.

These are NTSC files, and for good measure I ran them thru VCDgear…
NO problems there. Very puzzling. Any ideas?