Richard,
Never figured out an app that would allow for recording vid from an external source. Everything I found wanted to record from the onboard camera of my S4 (Android, so would apply to the Note 2, I would think). The tricks would be to find an app that would allow for this and then to figure out a wiring harness configuration that would go from the RCA output on the N750 to the mini USB on the Samsung. Might be a lot easier just to buy a MDVR. If you go the MDVR from Ultimate Night Vision, be sure to tell them it is for an N750. They have a proper video cable for it.
I gave up and went to an Angel Eye dvr (3 of them) and then to a MDVR that has worked very well. Would have been cheaper to get the MDVR first and a lot less hassle, though Angel Eye units are cheaper now than they were.
Pulsar makes a battery pack for the N750.