Just looking for a little education.
According to Apple's KB, iTunes handles mp4 files. So, using Freemake Video Converter, I converted some avi files into mp4's. It was very fast--just what I had been looking for. But iTunes won't import them either individually or the whole folder.
I then found Video Converter has an "Apple" setting which apparently converts into .h264 format. This seems to take longer than the direct to mp4 process, but iTunes imports them fine.
Shouldn't iTunes import the mp4's? Why won't it? What am I missing in my understanding of file formats?