Unfortunately, much of what he says isn't entirely accurate. The first thing the game tries to teach you (and it does this repeatedly) is to always be cautious, because pretty much any enemy in the game can kill you if you are too careless. Blindly sprinting through an unexplored area is dangerous. In the case of the dragon instakill, he was entirely at fault. If he made it to that point in the game, he must have already sucessfully crossed 1 bridge with a killer dragon. Any sensible person would be extra careful when crossing a silimar bridge in the same castle.
Being dead isn't really a handicap, because there are different benefits to being in soul form and human form. Some things can only be achieved in one of the two forms, and with a cling ring you max HP can be increased to 75%. If an enemy is in the middle of a combo, and you step back once, it makes sense that the other blows in the combo will hit you even if you avoid the first one. You also can't dodge properly unless your equipment burden is less than 50% of max.
If you plan to enchant a weapon with an item doing so from inventory is silly, it should be equipped in an item slot for quick access. The demon he faced, Phalanx, moves very slowly. If he put enough distance between himself and the demon, he should easily have been able to access the inventory to enchant his weapon. The game seeks to be tough, but fair. To that end, emenies that can heal also take the same amount of time as the player to eat healing items and are of course left momentarily vulnerable. That strict fairness is also one reason acessing the inventory does not pause the game. The only safe place to fully relax is the Nexus.
Finally, messages are used in many ways; they don't always warn of danger. Since they can be left by any user, they are sometimes completely false. Some tend to be somewhat humorous, like the message warning about the deadly fall one foot in front of the player. The messages can be rated by other users and the useless ones eventually disappear, so most of the remaining ones are actually helpful. The game is hard, but not prohibitively so.