I am trying to animate the intensity of the HDRI backdrop that is lighting my scene. I added the HDRI Backdrop in the sequencer by clicking the green “+ Track” button but the HDRI backdrop doesn’t have any options that I can add keyframes on.
How can I animate the intensity for a cinematic?
Same problem here, still figuring out a workaround but have not been succesfull so far.
Very unfortunate. Maybe animate the exposure level of the cam or Maybe there is a way to edit/animate the hdri material but it sounds like a hassle. Would be great to hear a solution if you found one!
I just ran into the same issue
Turns out you can can call the Intensity of the hdri backdrop by calling the “material parameter track” from the HDRI backdrop Geometry element
In the sequencer editor add your hdri backdrop element, then add a track into it calling the “geometry element”, and then add a track to the geometry track calling for “material parameter”
Then you will be able to call for the intensity and animate it
Thank you for pointing me in the right direction Stef 
I found out that is way more simple than i thought, You simply need to track the SkyLight Intensity inside the HDRI, You can change the color as well, as some other parameters.
Animating Skylight intensity looks different.
Instead you should animate geometry - materials
Open the HDRI Backdrop BP. Select the Intensity variable under at the lower left. Enable “Expose to Cinematics”. Save/Compile. Intensity will show up in Sequencer now.
