beta video controls will not appear after disabled settings > video > double tap for 10 sec skip AND brightness gesture
kept adding to report through play store beta feedback from 3.0.95 through 3.1.0 rc2
using S5 klte running LOS 8.1 Oreo 20190212 with OpenGapps
edit: also i can also reproduce this consistently (starting from video or directory view) with an HP Touchpad (tenderloin) running Cyanogenmod 4.4 Kitkat so...
but that seems to just be an email forward system and formatting gets mangled (now limited to 500 chars) so figured this would be easier for tracking.