Instagram is designed to present images and videos in either a square frame (Option A) or a cinematic rectangular 16:9 frame (Option B). You can choose which framing you would like for your video in the upload settings within the Instagram platform itself.
To do this – first select the video for upload in Instagram and then look for the double diagonal arrows icon in the bottom left hand corner of your video selection screen. Tap on this icon and you will see your video switch from a square 1:1 presentation to 16:9 rectangular proportions.
Bear in mind that unless your video has been shot on a phone held in a portrait position or shot especially for a square aspect ratio, your video footage is likely to have been framed in rectangular proportions. This means that if you upload your video to Instagram and choose the square framing your video footage will be cropped and you will lose some of the picture.