Not working as expected on Firefox.

[Botanistt]

Not working as expected on Firefox.

[tgomilar]

Hi,
It seems like objec-fit: cover; acts differently across browsers when transforming element.
Try setting starting position of video with some offset translateY(-Xpx) so that you get rid of the white space between video and its wrapper

#--cover .background > video {
  transform: translateY(-125px);
} 

and lower data-paroller-factor data-paroller-factor=0.5 so that video stays within wrapper while scrolling down.

Codepen: https://codepen.io/tgomilar/pen/djGYeZ
This solution doesn't solve the problem itself but it helps fixing this particular case so It doesn't look like a bug 😉

[Botanistt]

Hi. Yeah I later figured it might be related to object fit cover and managed to came up with a similar solution. Thank you regardless.