Hi -
I am currently using the blueprint method to make my levels full screen because the default user settings ini file approach doesn’t seem to work at all.
The blueprint approach is fine, except that obviously doesn’t apply to the startup videos. 
There has to be a way to do it, but I can’t seem to find it.
I don’t know how to play full screen videos, but I know that the default user settings. ini works, I used it before, but the problem is that there are multiple file with the same name you might have changed the wrong ini file. What file (directory) did you change?
I had the same issue, and I went through the same articles and confusion. You’re changing the wrong file. I have to go, but just give me some time and I’ll find the right article.
I changed the one in the config directory (It isn’t there by default, so I had to create it). I read the guides online, about not doing it in the “saved” directory, so I didn’t. It definitely made no difference to my packaged game.
I’m having troubles getting the startup video to play on a packaged Shipping version in 4.13. It works in Development. I’ve tried several different formats, but nothing is working.
Have you had any luck getting it to work?