I would highly recommend the UNV MDVR system. It is by FAR the most commonly used and trusted DVR in the NV world. Everyone from Sightmark Photon owners all the way up to Trijicon/IR Defense owners have been using the UNV MDVR for years. They have custom cables for most every NV optic including the N750's. It records audio and video and includes the remote record switch that quickly powers the unit on and starts recording within seconds and then instantly turns the unit off when you flip the switch off. It's a huge asset and battery life saver.
I you are looking at $195 for the MDVR and about $30 for the custom cable, but it's worth it. I'm not sure of anything else that will give you all the features, reliability and warranty that you'll get from the MDVR. It is also worth noting that you get a custom buttstock pouch with the MDVR that is awesome.
Night Vision, Thermal & Accessories
Pulsar, Sightmark, FLIR/Armasight, Trijicon & More