In order to use your custom USM file in Tekken 7, you have to follow this tutorial: Encryption Of USM Files
Your video must not have audio and must be saved in the Audio Video Interleave (.avi) format. Additionally, you must separate the audio and save it in the Waveform Audio File (.wav) format.
Downloading The Tool
Download 'Scaleform Video Encoder v4.6' from the link below: Scaleform Video Encoder
Using Scaleform Video Encoder
Select your 'WhatEverYourVideoIsCalled.avi' as 'Input Name' and select the output-directory and -filename as 'Output Name'. If you want to add audio to the USM file, set the audio settings from 'None' to 'Mono/Stereo' and select your 'WhatEverYourAudioIsCalled.wav'. Keep the codec at 'Sofdec.Prime (default), the video settings are up to you. Click on 'Encode' in the lower right corner once you are ready to create the USM file.