Hi Konrad
i have setup an dev environment for the website.
1. i have deactivated all plugins except acf pro and acf extended.
Testet with:
ACF Pro V5.9.4 And v5.9.9
ACF Extended: V0.8.8.4
The problem is not related to those videos:(
i have recorded a video to showcase the problem: https://imgur.com/a/lc6yhUk
if u want access to the dev environment for further investigation i can grant you access ??