Left or Right Swing Door
In or Outswing - Right or Left Hand
Exterior doors: In or out refers to inside or outside your house. Inswing means that the door opens to the inside. Outswing means the door opens to the outside. In-and out requires a reference point: from the inside. If you enter from the outside, you are in-swinging a door - the in refers to the house inside or outside - not the direction you are pushing. From the outside - you are pushing away from you, not pulling towards you.
For interior rooms: consider the room being secured being the inside. Same logic applies as above. If you pull your door to leave the bedroom - you have an inswing bedroom door.
Inswing is desirable - so you don't clothesline people in the hallway. Inswing is desirable for exterior doors for safety- if it's a break-in - you can push the door shut with your body. If the door swung out, if you decide that you have an intruder, it would be harder to shut the door in their face.
Ambiguous case: for a door between two rooms - it can be ambiguous which direction is inswing and which is outswing.
The ambiguous case makes you ask questions: 1. Is the door identical on each side? Then hinges can likely be remounted so you obtain inswing or outswing. 2. For handedness - is the door hinge on right or left side? If the door can function equally upside down, then the door could be right or left-handed.
This gets into how left and right hand is defined.
When you go up to a door, are you using your right or left hand to open it? That determines the handing. But that is not a transparent definition. If you go up to a door, you can open it with your right hand or with your left hand. For a person without a right hand, the left hand would be more convenient. So the right- left- distinction based on which hand you use is a poor one.
A door that has ambiguous in- or outswing cannot be called in-swing or outswing. It can only be right or left handed. The definitive way to define handedness is to open the door, put your back against the hinge. If the door handle is closer to your right hand, it is called right hand, and vice versa:
Both in- and out-swing-ness (even in ambiguous case) determines the right or left handedness. Handedness is thus not determined by:
- Whether hinge is on right or left side. When you look at a door from the outside - for example - its handedness will be different if it is inswing or outswing - regardless of the hinge being on the left side.
- It is not dependent on which hand you use to open it 'in the most convenient manner' - convenience may vary for different people - some may use right, others may use their left hand.
- It is not the direction that the door opens. This direction changes whether you are looking from the inside or outside, and this distinction may be ambiguous.
- One could not say 'when standing inside a room' - because which is 'inside' for 2 adjacent rooms?
Best diagram of cases is here: 
So for example, left hand in or right hand out are 2 different doors - but if one can remount the hinge from inside to outside (not a prehung door) - then one of these doors can serve both functions.
Another example: if a door is identical upside down (such as it it has no locking mechanism but has only a closing mechanism and is not prehung) and has no inside-outside distinction - then it can be used either as a left-hand in/out or left-hand out/in without any modification. You would need to flip it upside down to go from left hand-in to -out, and you would need to flip it and remount hinges to go from left hand in to right hand in - and you would need to reverse the hinges to go from left hand in to right hand out. See the diagram above.
The hardware such as a lever could also be left or right handed, while it may not matter for others. 
In and Out vs Reverse
Some call 'outswing' - 'reverse' . This is not consisent with the 'back to hinge' method of the youtube vid.
'Right hand' or 'left hand' refers to the hand that you use to open the door. The convention is that the door knob is on the right side for a right hand door, and on the left side for a left hand door.
In Seed Eco-Home 2 and 4, deck door is right hand inswing - opening towards the back wall so that we are not taking up space in the middle of the room.
Bedroom door for SH2 - all inswing so you don't clothesline someone in the hall, and have bedroom privacy from peeping toms.
SH2 and SH4 bathrooms are right hand inswing for ease of access prioritized over privacy.
The main design for bedroom door inswing: It provides just enough privacy to person/people in bed from anyone who may be walking down the hall or entering unexpectedly. Privacy is defined by not being able to see inside most of the room when the door is slightly cracked open, as the cracked opening faces towards a wall or corner. You could design for full visibility with a cracked door, or for limited visibility.