Motivation:

You have MP4 files with unwanted portions. You want to trim these portions.
You may also want to cut a MP4 file into files with equivalent length for uploading to specific storage that limits length of an uploaded video.

Solution:

1. Download XMedia Recode.
2. Install the application.
3. Open a MP4 file.
4. Under the Format tab set
   Profile = Custom
   Format = MP4
   File Extension = mp4
5. Click the Video tab and set Mode = Copy on the middle panel.
6. Click the Audio tab and set Mode = Copy on the middle panel.
7. Click the Filters/Preview tab and set Start Time and to (End Time).
8. Click Add to queue button (with the + icon) on the tool bar.
9. Click Encode on the tool bar.

If you want to split a MP4 file to multiple files by time then just repeat the procedure from the 1st step to the 6th step, then
7. Specify appropriate time range for each file, for example from 00:00:00:0000 to 00:09:00:0000.
8. Click Add to queue button (with the + icon) on the tool bar.
9. Click Encode on the tool bar.

Then repeat the procedure for the same file with different time ranges. For example use time range from 00:09:00:0000 to 00:18:00:0000 for creating the second file, then time range from 00:18:00:0000 to 00:27:00:0000 for crating the third file, etc.