LAFEAR, thanks for clearing that up for me. I love both PEnGUIn Encoders and have used them for a long time, and they just keep getting better.
Because the differences between the PEnGUIn Encoder M4V and the PEnGUIn Encoder MP4 are so small, I wonder if both the users and you would benefit by only having ONE PEnGUIn Encoder that can create either kind of filetype? You could probably explain those small differences between them with just one sentence, and perhaps another sentence could describe how to decide which one to use, and both could be right up front with checkboxes for users to choose whether to use the .mp4 or .m4v file extension for their newly converted video.
It's just an idea. Anyway, thanks again for all your hard work, and for offering them to us for free!