Yes I’m having been problems with video stuttering even with the extension of .m4v not changed.
I’m using the last f/W 2.21 they still havent fixed it. Been on futal tech support call and finially they gave up and passed it on to the engineering team. “Black Hole” No word since then.
There seems to be an encoding problem they have which originally I thought was bit rate issue but I can watch .*mkv files sourced from BluRay. perfectly no stuttering.
I measured around a 20 Mb/s sustained for the playback and that is much more than the m4v files.
Also experimented with different settings on handbrake VBR no VBR still an issue.
I believe they have to be aware of this but I here no admission of the problem on WD’s part.
My only common source of problem seems to be handbrake. Apple TV, PopCorn Hour plays the m4v’s fine. I only had to change extension to Mp4’s so Thumbnail setting would display Tag information. Which is another story with this box.