One solution to overcome the 4 GiB limit on OBB files in Android is to split the video file into smaller chunks and package each chunk as a separate OBB file. You can use the chunk creation feature in Unreal Engine to create multiple OBB files for the video. This will ensure that the video file is correctly installed with the .apk on the device.
Another option is to store the video file in a separate “Movies” folder outside of the OBB file, similar to how it’s done with Windows builds. This way, you can maintain the video quality without having to compress it further.
Note that for this solution to work, you need to make sure that the video file is correctly installed with the .apk on the device, and the path to the file is correctly set in your Unreal Engine project.
Edit: Another thing that hit me, would be to use something similar to an iFrame to stream the video from a server or website.