If I rotate the phone to landscape leftwise or rightwise -- both come out fine. However, it's only the rightwise rotated landscape video that was upsidedown when re-encoded from .mp4 to .mkv. 💡
🙂 yes, @Opolork : posts have specific topics, which makes them easy to find... so if someone has an issue, others who might have the same issue, or have had in the past, might be able to help, or get help.
Please NOTE that not all applications can work with the sd-card. I.e. the camera app has a feature for that, but I got frequent crashes with selecting external storage for pictures. This is maybe fixed in the current versions however.