So many technical issues

[Maasbommel]

The explanation is much simpeler.

Jumbo frame mode does not use RX/TX protocol.
It just assumes the receiving party is fast enough to receive what is thrown....
And by enlarging MTU the chunks thrown are even bigger...

When we talk about a mediaplayer it only needs to get the data fast enough to be able to play it real time, not faster. It needs to be able to say to stop the transmit (TX) and sent again when the buffer is almost empty....

So therefore Jumbo frames is not suitable for a MediaPlayer, in most cases data thrown at it comes too fast...
It needs an TX/RX protocol (start/stop).

Jumbo frames is more something to use for transfer files rapidly, not for media streaming.

[sibbels]

Just an update:

Last night, I played 2 MP4 files, both around 170MB, the first MP4 froze twice (the second time displayed the 'Stop playback' prompt), and the other MP4 froze only once but then resumed pixelated after about 10 seconds...

[jer1956]

MP4 is a package which can have different proproatary H264 codecs in it. That's why there are so many mp4 cross coversion tools.  You need to use Mediainfo  to  list the contents.