This article won't be about 'how to make VST to sync videos using VST', but rather work around how to make it work in Bitwig Studio (and also in another DAW).
Please remember to check licenses of that great software before use them.
"C:\Program Files\xjadeo\xjadeo.exe" -S -a -i 3 --midi-driver portmidi -m -1
more options on xjadeo cli arguments - here.
Right Click and File->Open or CTRL+O and select your video.
Start the loopMidi and create new Loopback Midi Port and name it for example "myMidiLoopback"
Drag and Drop the Video in the Bitwig (It will extract audio and place in the (best) Audio Track). Then change the audio clip to raw (select the Audio clip you just imported and in the Audio Event Properties -> MODE change from Stretch to Raw)
Go to the Bitwig Studio->Settings->Synchronization and click on MTC for "myMidiLoopback".
Now start playing music in the Bitwig Studio and you can see that video is syncronized.
note: You can make the video player window stay on top Right Click->Display->On Top or using short cut SHIFT+A (keep pressed bit longer as short may not work.)
note 2: You can shrink the video for a better performance using ffmpeg. For example:
# shrink your video to one quarter size. Change 8 to 4 for half size. ffmpeg -i yourvideo.mp4 -vf "scale=trunc(iw/8)*2:trunc(ih/8)*2" -vcodec h264 -acodec aac -crf 28 a_fourth_the_frame_size.mkv
So without extra VST plugins you can synchronize videos using just video player and MIDI.