The four stages of the Bel Canto technique are as follows:

The "lift of the throat:"  

In Bel Canto, the voice is NEVER directed towards the soft palate or the throat. This makes sense.... consider: you can whack a bean bag chair with a Louisville slugger and not make much noise... hitting a soft surface (ie soft palate, throat) is useless. You're much better off tapping your knuckles on the lid of a garbage bin. (less effort, harder surface, resonating chamber....) A lot of singers think they have to yell and scream to get any projection, but those voices tend to be absorbed in part by the soft palate. A lot of effort for little gain. Directing the voice at a hard surface (teeth, hard palate...) will give much better projection. 

Try smiling when you sing. Not a cheezy grin like someone is driving a nail into your baby toe kind of smile, but a more "open and relaxed" smile - like someone just complemented you on your new shirt, or like you've just recognized a friend in the crowd. By visualizing separating the upper and lower jaw at the back teeth, visualizing yawning in the back of the throat to open the airway, and singing with a relaxed smile - mouth turned up gently at the corners - the throat is relaxed.  If you actually DO yawn, you're probably doing it right. The result of this will be a lifting of the uvula (the punching-bag-thingy in the back of your throat). Your whole throat will be open and relaxed. Do this before you sing a note, and maintain this position at all times when you sing.  Lamperti said, "While sustaining a good, easy tone, open mouth as in a yawn..."  However, he also said to not open the mouth wider than a finger width.  This suggests that the openness is created not by dropping the jaw, but by a lifting and widening of the throat.

The "mask of the face:"  

This is pretty widely used in many techniques. Essentially, the mask is an inverted triangle where the higher notes are thought of as wide and just below the cheekbones, but in reality are placed wide across the dome of the hard palate. (the dome of the hard palate is just below the cheekbones...) Essentially, you are placing the voice "high" on the face.  The lower notes are in the bottom point of the inverted triangle, which puts them just in front of the lips and very narrow.  Focusing low notes very narrow and in front of the face brings in resonance from the chest more than it does for middle and high notes, but regardless of the pitch, the resonance is actually created in the sinus cavities.  In Bel Canto, just behind the teeth is the placement for "mid-range" notes.    This line of thinking is taught in other techniques as well...

The "inhalation of the voice:"

Okay.... here is where everyone thinks you're lost your mind.  They'll demonstrate trying to sing by sucking air backwards through the vocal cords as a means toward showing how silly and impossible it is.  You CAN NOT inhale the voice into the lungs, and expect the vocal cords to vibrate properly as the air passes backwards through them. That would be contrary to human physiology.  That said, here is the scoop in a nutshell. 

Lamperti wrote, “In starting a tone, do not push.  The sensation is rather that of inhaling.”  The sound is visualized as being drawn in from outside the body, (involves visualizing a "pulling in of the breath" ) with a stream of air hitting the hard palate, and passing over (not through) the vocal cords, and into the sinus cavities.  Air will not *actually* enter the body from the outside, but visualizing this taking place is helpful in achieving the end result.  Edward said, "It is important to concentrate on the inhalation of sound, not breath."

Now, in the video, Edward talks of this inhalation as if it is actually happening.  It’s a helpful way to visualize what is happening.  But even he, himself, said that visualization is used to achieve certain ends in singing.  Lamperti was even more direct:  "Always remember that what goes on above the throat are illusions, no matter how real they may feel or sound."     

The "hold of the breath:"

Contrary to popular conceptions, air is not pushed up and out from the lungs with the diaphragm muscles (though the diaphragm is important), but rather drawn out of the lungs by controlled air pressure. The diaphragm is pulled down in order to take in breath, so that there is adequate air to be drawn up from the lungs. With as much air in the lungs as possible, there is a strong "foundation" on which to support the breath. As a result, the goal is to (roughly quoting again) "maintain the diaphragm as if holding one's breath." In other words, you are holding the diaphragm in that downward position.  Air WILL escape from the lungs, as if it doesn't, no air passes through the vocal cords, and subsequently, no sound is produced. A more controlled amount from the lungs (minimal) will allow for more contol overall, and a stronger foundation will result in a more "supported" sound.  Lamperti said, “Do not hold your tone, spin it.  Hold your breath.”