How long will the osmo+ record with a 128gig card in 1080i?  I'm looking to see if I can record for an hour. Also can you download a pdf of a manual?

Scroll down to the bottom for the manual download.
http://www.dji.com/osmo/info

128GB is plenty for an hour in 1080i or 1080p. If you reach 4GB of data it'll split the video footage.

I think I get around 3.5hrs in 1080i on my 64G card.  The IOS version of the DJI GO software will give you a real time calculation of how much time record time is left on your card at the current frame size/rate. Not sure if the android version has that.  Keep in mind that you'll only get around 18mins per clip though.  It won't record a 1hr event uninterrupted.

You should watch out the skipping of frames every time the file size reaches 4G. DJI apparently has no solution to this shortcoming.