Unable to upload large videos

Expected behavior

Uploading a very large video (e.g. larger than 500mb) to the Media Library (either from the Media Library itself or via the block editor's Video block) should work without error.

Actual behavior

Sometimes the video fails to upload.

Steps to reproduce the behavior

You'll need a large video for this (over 500mb) for either scenario below.

Scenario 1

1. Open the WPiOS app and create a new post using the block editor
2. Add a video block
3. Choose the large video and wait for it to upload
4. Observe the image upload fails (it's hard to say if this will happen every time)
5. Go to the app activity log (Profile icon > Help & Support > Activity Logs > Current) and scroll to the bottom to see the latest logs
6. Observe an error in the logs similar to:

2020-09-06 20:00:20:394 🔵 Tracked: media_service_upload_failed <error_code: -1001, error_description: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo=

The request timed out., NSErrorFailingURLStringKey=https://public-api.wordpress.com/rest/v1.1/sites/xxxxxxxxxx/media/new?locale=en, NSErrorFailingURLKey=https://public-api.wordpress.com/rest/v1.1/sites/xxxxxxxxxx/media/new?locale=en, _kCFStreamErrorDomainKey=4}, error_domain: NSURLErrorDomain>

Scenario 2

1. Open the WPiOS app and navigate to the Media Library
2. Add the large video and wait for it to upload
3. Observe the image upload fails
4. Go to the app activity log (Profile icon > Help & Support > Activity Logs > Current) and scroll to the bottom to see the latest logs
5. Observe the same error as before

Reported by user on an iPhone 11 Pro Max, iOS 13.6.1, WPiOS 15.5 (15.5.0.3)

Additional info

• A user who tried uploading a 1.05 gb video could upload the same video using mobile Safari via Gutenberg web (https://wordpress.com/block-editor/) but not from the app (note: WordPress.com recommends videos smaller than 1 GB)
  • Cutting the large video in two and uploading each part separately sometimes worked for the user
  • The videos in question are .MOV
• Possibly related: https://github.com/wordpress-mobile/gutenberg-mobile/issues/1152

_{(internal reference: p4a5px-2D2-p2}

Start by reproducing the upload from the WPiOS block editor Video block and Media Library with a video over 500 MB, then inspect the Current Activity Logs for media_service_upload_failed and the NSURLErrorDomain timeout. Compare the app behavior with the WordPress.com web uploader and the related Gutenberg Mobile issue; done means large videos upload successfully from both app entry points without timeout errors.