Step 2: Send the video to the Timeline.
Do you like the 4K video recording on your iPhone 6s? The original video I shot in landscape format was great and I would love to use it — I do not care if there is quality loss or anything like that.
Select the videol in the media browser to display it in the preview screen.
Finally, click on the share button, as well as, the save video option to convert the vertical video to horizontal.
However, it is invalid on your Mac.
If you accidentally record video on your iphone in vertical mode, you end up with two ugly black bars on either side of the video when viewing it on a tv.