iOS 7 - how much time we are allowed for background update?

iOS 7 - how much time we are allowed for background update?

From the WWDC video 204 - what's new in multi-tasking.
I got confused with how much time we are allowed for background updating.
here are the two slides:
First:
Limited Time in Background
Apps given limited time to update content and UI
• Given **less than a minute** to finish update
• Fetched in parallel with other apps
■ Optimize launch and fetching paths for CPU usage
■ Use Time Profiler in Instruments
• Important to complete as soon as possible
second:
Background Task Completion Changes
From background activity
• When woken for
■ Background Fetch
■ Remote Notifications
■ Background Transfer
• Background tasks are only given **seconds rather than minutes** of run time
As we can see from above, the first slide saying we have less than a
minute to do background update, the second slide saying we have seconds
rather than minutes to do background update, why this is different? for my
understanding we can only use those three methods(bg fetch, remote
notification, bg transfter) to do background update, does this mean we can
only use seconds for backgrond update? if you want to download a video in
background, seconds is not enough.
can someone give me a clue in case I misunderstand the concept, thanks.
-- Justin.