Question: how do i download a video from dropbox to my iphone?
Answer: If you have Dropbox app already installed on your iPhone, launch it. ... 
Click "Data Settings" on iPhone, select "Dropbox" option.
A pop-up window opens up. ... 
Select videos (which you wish to download) from "Public" folder. ... 
Click "Download" button located at the top-right corner of the window.