What is the difference between these 2 videos? - ffmpeg

Question

I am using fluent-ffmpeg to resize a video.
I can't figure out what's happening though. I have 2 video files, one works but the other doesn't. I've been scouring the mediainfo outputs of both files, checking for discrepancies but other than filesize, duration etc. there's no difference (same codec, format, width/height, frame rate etc)
Here's a link to both files.
I've been reading these video files into fluent-ffmpeg using an input stream, as so:
await new Promise((resolve, reject) => {
ffmpeg(file.stream)
.output(path)
.size('426x240')
.on('start', function() {
console.log('started');
})
.on('error', function(err) {
console.log('An error occurred: ' + err.message);
})
.on('progress', function(progress) {
console.log('... frames: ' + progress.frames);
})
.on('end', function() {
console.log('Finished processing');
resolve();
})
.run();
});
The working file prints:
started
... frames: 86
... frames: 107
Finished processing
But the non-working file doesn't seem to have any frames, and prints:
started
... frames: 0
Finished processing
Any idea what could be wrong?
The ffmpeg command being executed:
ffmpeg -i pipe:0 -y -filter:v scale=w=426:h=240 uploads/works.mp4

Answer 1

I've been scouring the mediainfo outputs of both files, checking for discrepancies but other than filesize, duration etc. there's no difference
It does, but in full mode only. try mediainfo -f on the files, you'll see:
IsStreamable : Yes
for the working file, and
IsStreamable : No
For the non working file.
a "no" here means that the input needs to support seek (header is at the end, player needs to seek to end for parsing header then seek back to beginning for parsing data).

Answer 2

It seems like ffmpeg have problem probing the file when you pass it as a stream. But it does work if you pass it as a file. Could be because probing/demuxer can optionally use seeks etc. I tried to increase the probe buffer but didn't get it to work.
This do not work:
cat doesnt_work.mp4 | ffmpeg -i pipe:0 test.mp4
But this works:
ffmpeg -i doesnt_work.mp4 test.mp4