We see the shot panning through the Earth's atmosphere at an alarming rate. It flies past ocean waves, desert storms, while getting more close-up all the time.

'They're back – and even though our heroes have defeated the enemy, their fate may soon depend –'

The camera slows down as it approaches an island in a dried-up riverbed. The tree on top is huge, as is its roots and the anthill nearby.

'– on one insect.'

A flash of white light envelops the area, blinding out everything. When it fades, it is very dark, in an unidentifiable area.

'Something has arrived –'

Something huge and dark lumbers over the dark horizon. The only thing visible on it is what appears to be moving boulders, moving in harmony like huge, heavy clubs.
Several insects, including a ladybug, a stick insect, a fat caterpillar, two pill bugs, and three ants run behind a small cliff face. One of the ants, a blue one, peeks out from behind the corner, gasping silently at the huge thing.

'– a force with the power that could threaten all of their lives.'

Another shot-change, and we see a clumsy-looking grasshopper and the blue ant looking at an inside cave wall, with inscriptions and detailed drawings on the wall.

'This year, prepare for an all-new challenge.'

Elsewhere, the blue ant and the clumsy-looking grasshopper are running as fast as they can. The grasshopper buzzes his wings and takes flight, picking up the blue ant as he ascends.

'And see how one invertebrate –'

The grasshopper turns toward the screen, and then looks determined and brave, clutching his hands into fists.

'– will make all the difference.'

A rhino beetle flies upwards, with the blue ant on him, as well as a purple royal ant with membrane wings and a flower crown. They looked overridden with excitement as the beetle flies higher.
The beetle turns around in a hurry, bracing himself for battle, opening his legs out.
The two pill bugs bounce off a solid rock wall, and start squabbling over something inaudible.
The rhino beetle stops flying forward, and stays level. He roars as he looks across a stone bridge suspended over water. On the other side in the thing from earlier; a giant collection of boulders in the shape of a muscular insect, moving together in perfect harmony – a drone golem.

'New challenges!'

A wave lashes out of nowhere, causing a small shake. The clumsy grasshopper is flung forward, landing with a thud on the ground.
A black widow spider shoots a web rope upwards, latching it onto the rock ceiling. It launches her upwards, and the ladybug, stick insect, caterpillar, two pill bugs, blue ant and the brown grasshopper grab onto her, bringing them all up.

'New insects!'

A whole squadron of locusts charge forwards, holding spear guns in their hands.
We see a female ladybug, a female stick insect, a female caterpillar, and two female pill bugs looking with awe at something we can't see.
Another insect steps out of the darkness – an average height, angry-looking locust, with scars all over her body, making her look even more fearsome.

'A new adventure!'

Several drone golems fall over in succession, knocking over each other in a domino effect.
The rhino beetle flies past shaking rocks, narrowly missing a jet of water exploding from the rocks.

'Get ready for the greatest adventure they've ever had to face –'

The drone golem lets out a giant roar, and raises all four of its arms, ready to use them as battering clubs.

'– with insects you've never seen before!

'Groudon202 Hopper presents – A Bug's Life: Adventure Of A Lifetime!'

'Rock on!' said a small kid purple ant, buzzing just above the ground with her wings. A curled-up grass tiara was noticeable on her head, around her antennas.

'Only on the internet this Thanskgiving.'

There you go! Hope you could picture it as a trailer in your head - I tried my best.