I snapped a video today which was rotated, where I needed to flip it.
o Looking it up, there were _many_ ways, one of which is shown below.

If you know of a better, easier, more effective rotate, let us know.

How to rotate an entire cellphone video 90 degrees in Shotcut freeware
1. Download & install Shotcut freeware from http://shotcut.org/download/
2. Make a copy of a small smartphone test video, e.g., "test1.mp4".
(My test video was about 60 seconds at about 60MB, aka 60,000KB.)
3. Start Shotcut (mine was version 20.07.11) and open the test video:
File Open File test1.mp4
4. Make sure "View Filters" is set & click the "Filters" tab.
5. In the Filters tab, click the "+" icon (aka "Add a filter").
6. Select "Rotate and Scale" & set the "Rotation" field to "90.0 deg".
7. Click the "Export" tab and then the "Export File" tab.
8. Choose a new name, e.g., "test2.mp4" & press the "Save" button.
9. At the top right, a "Jobs" window will show the 0-to-100% progress.
10. Voila! When the job is 100% finished, you have a newly rotated video.

As always, please improve so that all benefit from every action you take.
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The high cost of freeware is in finding & testing those that work best.