Navy OCS 07-98 D.I. Introduction

I saw a training video in my NROTC class, and it's the same drill instructor.

Never did understand why a Marine would train Naval Officers. Wouldn't another Naval Officer or Senior/Master Chief Petty Officer be more appropriate? Any enlightenment would be most appreciated

Because Marines have thee highest standard of discipline in which any officer (Navy or Marines) should be held to in order to make a fine leader.

This could be NROTC which trains both Marines and Sailors.

No it's Naval OCS.

hes not just a marine, he is a Drill Instructor, even being a Staff Seargeant or above doesnt make you a Drill Instructor, you have to a go to DI School.
DIs are trained to Teach thats why they teach in different sub-branches....
Common Officers dont know how to master the way of yelling and make recruits mentaly tough....

Marines have almost perfect disipline and are known for that.

YOU GOTTA BE SHITTIN ME

The reason is so that there is not backlash. Only enlisted are DIs etc. and after OCS graduates technically have power over all enlisted, but Naval officers do not have power over Marines unless in their direct chain of command for whatever reason. Additionally Marines are more highly trained as DIs etc. thus they are the natural choice. In addition, even though Marines and Navy are different branches they are the same department.

Its because the Marines are a branch of the Navy.