HOW TO SAVE
There are several reasons why you might wish to save a video directly to your phone. The most common reason is to post the video to Instagram, which does not allow posting from a computer.
The 2 most common ways we deliver Instagram files are through email attachments (iCloud Drive attachments if the file is too big for your email provider) or via Google Drive.
Sent as Email Attachment
Example: Mail app in iOS 10.
Sent with Google Drive
Example: Google Drive app in iOS 10.
Once you have saved, you're ready to post to Instagram.