Below are two screen shots of a sequence that I made first with a audio File MP3 and then the same sequence file where I substituted a MP4 file in settings. Notice the bottom line "Garage Mats, Strand1, Node 1". This is a 'dumb' single color light mat. Compare this to the MP3 version. notice the added effects between ~17.5 and ~30 seconds in the sequences. This occurs in several locations within the timeline and for different models.
This has been driving me a bits nuts. All of my sequences exhibit this problem.
The MP4 files were generate from the MP3 file in iMovie, with a short text message at the very beginning to indicate the music selection in the display.
Any ideas why this happens?