I can look into that (I never make videos and am a bit unfamiliar with the process…)
Here is a written description on how to get the achievement. Anyone is also welcome to join me on discord to watch me do it via shared screen.
Play on Faster speed until first reinforcements arrive.
Build 2 medivacs and some scvs. First medivac heads left and picks up goliath / marine.
Reinforcements arrive in main base. Slow game speed down to lowest setting.
Defend ling / muta attack at main base. load remaining medivac with 8 marines and head to roof by 1st objective. Unload near the objective and marines will automatically do the job.
Second medivac (one that arrived as reinforcements) follows first built medivac to the left, navigating inbetween hydras to the roof which spawns 6 marines. Unload first medivac with goliath and marine to clear out a hydra or two. Send one medivac with 4 marines back to main base while the other medivac picks up remaining marines and reinforcements on building just above (+2 goliaths…)
Goliath medivac heads to reinforcements just outside of objective #2 (marauders and marines). Unload, stim, run directly to the right, kill a few lings and a few roaches (it’s ok to leave 2 roaches alive and taks some damage). Your goal is to kill the egg that begins spawning before it finishes. With stim and focus fire + goliaths, you have enough damage to kill the egg, then clear the remaining roaches and lings (target fire to save as many units as possible), then focus fire on the objective #2.
As you’re completing the above paragraph, objective #1 should be near dead, and your final medivac you built should finish up, load about 4 scvs up, and group @ objective #1. Your medivac with 4 marines that is returning from the north-west will pick up the remaining units @ objective 1, and all 3 medivacs should be full. (There is 1 last wave of 2 mutalisks which show up right after the objective #1 dies, kill the mutas, load all 3 medivacs up, then fly straight to the left (pretty much where kerrigan is). Avoid the spore and brutalisk.
Your units at objective #2 should have it about half dead. Be sure to stim, and focus fire any enemies that come to attack, then always reattack the objective (they will target other random stuff if not told to, and this objective has to be killed quickly.)
Unload your 3 medivacs just beyond reach of the 2 spores (bottom right side of objective #3), pre-stim your marines, finish unloading, and move directly left. Do Not Attack any units. As soon as you’re in range of the objective, begin focus firing it, and stutter step attacking as you continue moving below and to the left of it.
Meanwhile, your units @ objective #2 will be close to killing the objective, but will also be attacked by a wave of broodlings and zerglings which you can easily focus fire down and then be sure to return to attacking the objective and stimming marines. I was able to kill objective #2 @ 3:00, and it has to die before objective #3. Killing objective #2 will trigger the long audio cutscene.
Units at objective #3 continue to attack the objective only (attacking anything else will trigger more units to hatch). Your medivacs can do some last second healing on the marines and the marines can stim a second time if you position well. Objective #3 should be killed around 3:18 in order to make it through the final audio cutscene. Mission has to be completed by 3:30 in order to receive credit (a long mutalisk always begins hatching @ 3:00 and finishes @ 3:30 - this is not killable or avoidable).
Tips) Goliaths @ objective 2 are the real dps on the egg that is hatching. Be sure you don’t block them off from attacking the egg. Always stim a second time as well.
Tip #2) The scvs and 1 goliath @ objective #3 are a must, as they help soak damage and defend the marines, which are the real damage dealer. Stim a second time to get that extra damage in.
Tip #3) Save often - Play on slowest speed.
Tip #4) Focus fire broodlings and lings @ objective #2 when they come in, or else your army will die. As mentioned, objective #2 has to be killed around 3:00 to trigger the long audio cutscene. Stim those marines a few extra times as able.