How can I find out the size of a video file on my iPhone 6 camera roll? How can I find out the size of a video file on my iPhone 6 camera roll without connecting it to a computer.
The Shortcuts app made this actually rather easy nowadays. Configure it as an extension for the share sheet, then activate it in any video (or photo) within Photos.

PS: Shortcuts is part of recent versions of iOS. For first time users it might help to have a look at the Shortcut Manual.