That converter did the trick for some files, but rendered other files completely out of audio synch.
No matter… I decided that it was worth it to me to re-encode my movies to MKV files. This time, with some better options & settings for higher quality. Sure, it’s a bit of a pain, but the end result is so nice! I especially like having chapter markers work. I still wish the MP4/M4V issue would be fixed, but I won’t let it keep me from enjoying this device. I’ve gotten way too hooked on the other features, especially Netflix, YouTube & Pandora integration. And now I have a motivation to make better MKVs!