An encoder is a piece of software that takes your video and converts it into the digital "code" that your video CD software can understand and work with. When you view a digitized video, a decoder processes the data back into video. These are alsoreferred to as "codecs", that both encode, and decode.
I would start by going to the software manufactures web site and seeing if they have any encoders or "codecs" that are "plug-ins" for the software. These will work best with the video CD software.
Next, try some of the download sites like zd-net, cnet, no-nags, or completely free software. They all have an assortment of software products for file format conversion.
If your software can process other mpeg video, it is possible thatwhoever created this mpeg used a special encoder.