Video is flipped upside down on the Skype for Windows Mobile 10 Universal app15
Ironically, even though the app is made for the Universal Windows Platform, the PC version of it is not experiencing the same issue. According to some Windows 10 Mobile users, the bug that flips the video upside down affects all handsets running the platform. While Microsoft has tried to exterminate the bugs by updating the app, up to now it has been to no avail. There is one suggested workaround. The bug disappears in landscape mode.
The sad thing here is that Microsoft owns Skype, so you would think that it would be able to offer an app for Windows Mobile 10 without issues. On the other hand, the company does make more money licensing its Android apps than it ever made selling Windows Phones, so perhaps this never was a priority.
Priority or not, Microsoft is still planning on fixing Windows 10 Mobile bugs so there could be another attempt to send out an update that corrects the upside down images. Until then, if you are using a Windows 10 Mobile phone, you might want to make Skype video calls in landscape.