What you don’t want to happen is for the bike to rotate around the back wheel, and face plant you to the ground.
Normally, you bike doesn’t rotate around your combined Centre of Gravity because both wheels are on the ground, so as long as your mass is somewhere between the wheels all is good.
When you ride off a drop, the front wheel gets their first, how much sooner than the back depends on how fast you are going of course. Because you and your bike have inertia, it takes time for the bike and you to start to rotate.
So basically you have 3 options for drops:
1) Ride so fast off the edge, the short delay between the front wheel being unsupported and then the rear wheel being unsupported is not long enough to allow the bike to rotate forwards (this works for small drops on fast trails) and as a rider you don’t need to do much
2) Stay centered on the bike, and dynamically un-weight the wheels just before they leave the edge of the drop. Here, you deliberately pump down hard into the ground BEFORE you get to the edge, so as the bike (and you) bounce back into the air effectively both wheels leave the ground at the same time (even though the front wheel is over the drop first). Here you need to link the size of your pre-edge “pump” to your speed towards the drop. The slower you are going, the longer you need to unweight for, and hence the harder you must pump
3) Get your mass back, as the front wheel leaves the edge, to hold up the front wheel and to make sure your weight is being held up entirely by the rear wheel, so not resulting in the front wheel dropping.
In most cases, most drops require a combination of all these techniques.
(ie you’ll see trials riders rear wheel pedal kick hopping down off things, and SH riders just sending it off the edge at warp9 with hardly any change in body position)
And in all cases, it’s not the size of the drop that is important (it is mentally important of course) so nail your technique at various speeds on a small kerb, then work upwards. As that video proves, sticking your front wheel off a 4 foot rock drop with little of no technique ISN’T going to end well!