Here I included an example of a custom uuid USMT->MTDT block in a Sony PSP MP4 file

06A55450   75 75 69 64  55 53 4D 54  21 D2 4F CE  BB 88 69 5C  uuidUSMT!.O...i\
06A55460   FA C9 C7 40  00 00 00 90  4D 54 44 54  00 04 00 0C  ...@....MTDT....
06A55470   00 00 00 0B  55 C4 00 00  02 1C 00 22  00 00 00 04  ....U......"....
06A55480   15 C7 00 01  00 50 00 53  00 50 00 20  00 56 00 69  .....P.S.P. .V.i
06A55490   00 64 00 65  00 6F 00 20  00 39 00 00  00 26 00 00  .d.e.o. .9...&..
06A554A0   00 01 2A 0E  00 01 00 54  00 68 00 65  00 20 00 67  ..*....T.h.e. .g
06A554B0   00 6F 00 64  00 66 00 61  00 74 00 68  00 65 00 72  .o.d.f.a.t.h.e.r
06A554C0   00 00 00 32  00 00 00 03  55 C4 00 01  00 32 00 30  ...2....U....2.0
06A554D0   00 30 00 37  00 2F 00 30  00 32 00 2F  00 32 00 33  .0.7./.0.2./.2.3
06A554E0   00 20 00 32  00 30 00 3A  00 33 00 31  00 3A 00 33  . .2.0.:.3.1.:.3
06A554F0   00 34 00 00                                         .4..

The title “The godfather” is encoded in UTF-16 at position 06A554A7. To know a little bit more about the Sony PSP way of storing titles read this.