For converting an M2V file into a huffyuv AVI, you could try using VirtualDub-MPEG2 or VirtualDubMod. These will read the file and should correctly identify the framerate, then it's a simple process to set compression to huffyuv and save out an AVI.
Nothing wrong with making a huffyuv AVI, if you have the disc space. There are more elegant solutions, such as using Premiere plug-ins to read the M2V file directly, or a plug-in to read AVS files in conjunction with DGIndex and MPEG2Source().