I've read the Q&A and found:
Q: A few seconds are missing at the beginning of the video.
A: Enable Expert settings, go to Settings > Video > Playback and set "Pause during refresh rate change" to the amount that is missing
But I can't see this option (not even on expert).
It looks I have a delay of 5/6 seconds. Also when I close a video. Anyone has any ideas how to fix it?