Occam's Razor postulates that the simple solution is often the right one. That does not mean it's always so. For the longest time Occam's Razor would have favored a flat earth, before we knew better.

Alien intelligence would also be alien enough if it wasn't interstellar. Interplanetary, inter-dimensional or subterranean would be alien by my standard, too.

The Videos might have been plausibly explained, but i would argue that the pentagon has certainly more footage and sensor data to base their statement on.

And please do try to take photos of planes in the night sky with your smartphone camera. The image quality is not great.