They're normally accompanied by MOFF files, THM files, images, and M2TS or MPG videos. The file might look something like filename.m2ts.modd to indicate that it describes details on an M2TS file ...

A THM file cannot be converted directly to an MPEG. However, ... After opening the program, click "New Task" on the menu, browse to find your movie file, then click "Open" to load it.