1080p videos do not play as startup movies, and there is no indication as why given by the editor. 1080p videos will work with media framework. There is no documentation either, so there is no indication given why these files are failing to play.
There will be a black screen instead of the video playing.
Movies that are 1920x1080 will play as expected.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-65073 in the post.