all right, if TMPG DVD Author will not import the 2nd video, then it is likely a problem with the file being non-compliant to DVD specs.

if you get ReStream and simply open the .M2V file, it will tell you the resolution, frame rate, etc.

sounds like this 2nd DVD was authored with something like DVDLab - which will accept non-compliant MPEG files and compile them to DVD anyway.

hence, you may want to try out DVDLab for re-authoring the DVD (with both shows).