If I watch a battle and set the speed to other than 1X, watch it, and then hit the replay button, it resets the playback speed to 1X. It also does not remember the speed setting for my next battle.
I still have to push for the cinematic mode being more a series of still camera shots. It is poor movie making and does not show off all your work very well at all. Also, it needs an RNG. It shows the same sequence over and over as you replay.