Videos files recorded on most phones were coming in sideways; files
recorded on some laptop cameras were coming in upside down. In both
cases the display_matrix metadata of the video stream was not applied.
This required changing internal container format of movie proxies to
be MP4 instead of AVI, since AVI does not support rotation metadata.
File extension kept at ".avi" to not disturb existing expectations.
It might be better to "bake" rotation into proxies while building them,
but right now we do not have a trivial way of doing that.
Note that this is a potential behavior change; if someone
already had manually rotated video strips, they would have
to undo that rotation now.
Pull Request: https://projects.blender.org/blender/blender/pulls/130455
611940805e