ffmpeg -i https://public.ynjn.jp/collection/3ccd186d07a9a99a24cd5c67f09588b2/streaming/d4t3hoqp9kodv2doh0oga1hxkn960wma.m3u8 -c copy kanemaru-saki.behind-the-scenes.mp4

$ ./devel/copyclips/showboxes.scm /tmp/kane.mp4
ftyp 32 bytes at pos 0
moov 1110034 bytes at pos 32
*mvhd 108 bytes at pos 40 0 over minimum
*trak 894707 bytes at pos 148
**tkhd 92 bytes at pos 156 0 over minimum
**edts 36 bytes at pos 248
***elst 28 bytes at pos 256 -4 over minimum
**mdia 894571 bytes at pos 284
***mdhd 32 bytes at pos 292 0 over minimum
***hdlr 45 bytes at pos 324 12 over minimum
***minf 894486 bytes at pos 369
****vmhd 20 bytes at pos 377 0 over minimum
****dinf 36 bytes at pos 397
*****dref 28 bytes at pos 405 0 over minimum
****stbl 894422 bytes at pos 433
*****stsd 194 bytes at pos 441 15 over minimum
*****stts 274352 bytes at pos 635 274320 over minimum
*****stss 2352 bytes at pos 274987 2336 over minimum
*****ctts 193640 bytes at pos 277339 193624 over minimum
*****stsc 179392 bytes at pos 470979 179376 over minimum
*****stsz 137192 bytes at pos 650371 137172 over minimum
*****stco 107292 bytes at pos 787563 107276 over minimum
*trak 215114 bytes at pos 894855
**tkhd 92 bytes at pos 894863 0 over minimum
**edts 36 bytes at pos 894955
***elst 28 bytes at pos 894963 -4 over minimum
**mdia 214978 bytes at pos 894991
***mdhd 32 bytes at pos 894999 0 over minimum
***hdlr 45 bytes at pos 895031 12 over minimum
***minf 214893 bytes at pos 895076
****smhd 16 bytes at pos 895084
****dinf 36 bytes at pos 895100
*****dref 28 bytes at pos 895108 0 over minimum
****stbl 214833 bytes at pos 895136
*****stsd 123 bytes at pos 895144 -56 over minimum
*****stts 24 bytes at pos 895267 -8 over minimum
*****stsc 40 bytes at pos 895291 24 over minimum
*****stsz 107296 bytes at pos 895331 107276 over minimum
*****stco 107288 bytes at pos 1002627 107272 over minimum
*****sgpd 26 bytes at pos 1109915
*****sbgp 28 bytes at pos 1109941
*udta 97 bytes at pos 1109969
**meta 89 bytes at pos 1109977 0 over minimum
free 8 bytes at pos 1110066
mdat 2882851964 bytes at pos 1110074
$ stat /tmp/kane.mp4
  Size: 2883962038      Blocks: 5632744    IO Block: 4096

-empty_hdlr_name true -use_editlist false -write_btrt false -write_tmcd false

‐-､/