Redmi 4 supports OTG. All you need to do is get one OTG cable (find them here). So now watching movies which are in the pendrive is no more a problem. Just insert the cable or the pen drive(OTG) and go to the explorer. You will see a folder. There you can access all your files on the external storage.
You can get OTG pendrives here
The same pendrive I suggested to my girlfriend as well and it works great with her Redmi 4.
You can find the whole specs: Redmi 4
Yes Xiaomi Redmi Note 4 is compatible with VR. Xiaomi Redmi Note 4 has a feature gyroscope sensor which makes the device to get compatible with VR.
I would like to tell what features you need to check
Lens: Without the quality lens, the viewing experience will be poor. The size of the lenses matters
Field Of View (FOV): The viewing angle should be at least 90 degrees. This helps you in giving you theatrical experience.
Wireless Gamepad: For certain apps, youll need a wireless remote controller/gamepad. It would be better to buy it along with VR headset to get that real VR immersive experience.
Adjustability: We all have different face structures, so unless the Inter Pupillary Distance (IPD) is adjustable, it would be tough to get the clear quality vision. Also, the usage should be easy
Weight: Choose VR headset with as light weight as possible (preferably less than 350 gm). When used with your smartphone, the weight will increase.
Smartphone compatibility: Most of the VR headsets are compatible with any smartphone of size 46 inch.Mobiles which has gyroscope sensor are compatible with VR headsets.
Look and feel: buy a trendy and smart looking VR device.
Heat dissipation: Unless there is good ventilation, your smartphone gets heated up fast.
QR code: For viewing VR videos on Youtube, youll need a QR code to suit the VR headset
My recommended VR headsets-(click here)