Video cut off after 15 minutes
If you view a video in the Dropbox web page then it will play only the first 15 minutes. To see a video longer than 15 minutes in full, please download it.
This is simply a limitation Dropbox applies.
Dropbox comments not in use
Tue 5 Jul 2016, when logged in and accessing files, please do not use the Dropbox comment facility as it is not monitored.
Thu 22 Oct 2015, a new video was added to the help page. Listed under How do I view or download files? → A quick video intro it provides a quick tour covering accessing a collection of files and downloading & viewing files.
Tip: FAQs build
On the help page most FAQs follow on from each other, so to help understand an FAQ it can sometimes be helpful to read one or two that precede it.