I tried very quickly this morning, after trying to play the same files yesterday evening on my Mac. Just for the record, the third file (the 650MB one) struggles on it as well (though, it is not wired in this case but on WiFi), and as I already copied the file on an external hard disk to test with the RPi, I tried playing it from the hard disk and it is perfect on the Mac.
I then tried to hook the HDD to the RPi but it wasn’t able to supply enough power (at least that’s my impression) so the HDD was constantly powering up and stopping. I then copied the test files on an SD card and hooked it to the RPi using a card reader. The results? The first file plays flawlessly as it always did, the third one is played flawlessly (so, some network issues here are the culprit, and this to my astonishment as, while it still worked, I played without issues a 4,4GB / 1080p / 90 minutes clip file on the same network on an ATV with OSMC installed, that to my understanding is heavier on the network than a 650MB / 20 min file. As the ATV still has problems*, I couldn’t test if the network issue is only related to the RPi or not). Nevertheless, the problem on the second file still remains even if played locally: video stutters, and after few seconds a noticeable delay (various seconds) in audio starts to happen (I’d say that audio is played at the right speed while the video remains behind) and artifacts start to appear.
Could it be that this is related to the “H.263” which we see in the “Format settings, Matrix” of the media info?
“*” I’m still struggling with this problem: Can't play network files, streaming works flawlessly which sometimes also afflicts the Rpi as well.