For the reproduction of video files in MB STUDIO the correct installation and configuration of the LAV video codecs is required
Download the codecs in the standard package from this page: https://codecguide.com/download_k-lite_codec_pack_basic.htm
After installing the codecs open the "Codec Tweak Tool"
Click on Win7DSFilterTweaker: Preferred decoders in the 32 bit column set all the options available on LAV Video
click on "Direct show Filters" click on LAV Video decoder and configure everything as in this image:
click on "LAV Audio decoder" and disable the option "Enable System Tray Icon"
click on LAV Splitter and configure everything as in this image:
In windows, enable the display of all notification icons:
This is necessary because you have to check that while MB STUDIO plays a video file, the red icon LAV VIDEO + the white LAV icon in the taskbar indicates that MB STUDIO is using the right LAV codecs
If the red + white LAV icon is not present, it means that MB STUDIO is not using the provided codecs and video may be black or completely out of sync or other malfunctions.
To speed up video mixes in MB STUDIO enable video prebuffer:
from Control Panel click on Power Options and set "High Performance"