I did put a MP4 vid as splash but removed it, because the game doesn’t seem to like it and is crashing with a send crash report.
What video format should I use?
It normally should work with mp4. Make sure to take a look at this thread: https://forums.unrealengine/showthread.php?51160-Starting-Movie 
H.264 is the best option for the codec.
thank you for the info
I compressed it new and is working now