On my test phpBB board (http://59plymouth.net/59test/viewtopic.php?f=49&t=3351) I have uploaded a .mov video three different ways from the iPhone on which the video was produced:
1) I emailed from my iPhone to an account I accessed on Windows 8.1, extracted the attachment, and uploaded to my board from Windows;
2) I directly uploaded from my iPhone to my board; and
3) I attached my iPhone to my Windows 8.1 computer, copied the .mov, and uploaded from Windows.
Apparently, the iPhone scaled the video in (1); about 8MB on the iPhone (according to a Windows browse of the device in (3)), it was less than .5MB in the email attachment. Nonetheless, after upload to my board, and download back to my Windows computer - it plays in the default Windows Media Player.
If I download the .mov that was uploaded by iPhone in (2), it is about 4MB - roughly half the size of the actual video on the iPhone. It will not play in Windows Media Player. Curiously, it will play in VLC for Windows.
If I download the .mov that was uploaded from Windows in (3), it is 8MB, the actual size on the iPhone. It will play in Windows Media Player.
When I click on the link for (1), (2) or (3) on my iPhone, the iPhone immediately attempts to play them - and fails for all of them. There is no opportunity to download.
Whether the .mov is uploaded directly from my iPhone - or, copied to Windows and uploaded from there - the download experience should be the same. But, it is not. The file size is about half of what it should be by direct upload from my iPhone.