I think one of the biggest points that has barely been touched on is the content of the videos...Mass Effect 3 takes place some time around 2186..as you can see from the leaked intro you posted, Earth's cityscapes look VASTLY different than anything in these videos...why would Bioware make viral vids showing an apparent precursor to a Reaper invasion almost 200 years before it ever happens? Bioware isn't that stupid...plus.. the last game on Earth that would NEED a viral marketing campaign is Mass Effect 3... plus, the sounds don't sound that alike, much less "Exact" as the OP keeps stating.

Just wondering if we can rule out viral marketing yet?
This theory seems less plausable with each passing day.

Ive never even heard of this game

I still don't see any proof.

I just heard this is viral marketing for the new Mario Kart

Not sure if anybody else is keeping up with this, but the sounds in these recent videos are EXACTLY THE SAME as the sounds of the Reaper invasion in the Mass Effect 3 demo, There's even a cut scene where a little boy covers his ears as the horn sounds.

Read through the thread and 20 other threads in this subject. It's like the same conversations and ideas are beig copied and pasted to each page.

It's not viral marketing.
It's not fracking
It's not haarp
These sounds are more than likely NOT man made if you ask me

I will be back to post after the game is released. And even then, when the theory presented here, by you, doesn't pan out.
You will still maintain that it's a viral for ME3. Even as you are playing it. That's my prediction.
The only person this was a viral for, was you, made up, in your own mind.
Who's delusional here? Ain't that a case of the pot calling the kettle black?
Anyways, talk to you again in a couple of weeks.

Even if this was viral marketing it would be stupid to drag it out this long. At this point it's losing it's hype and people are beginning to care less because it's becoming more and more common. They'd want to do this while it's at it's hottest, which was about 2 weeks ago.

And if it was it would be even dumber because it would be a HUGE let down/bummer to more people than it would be cool. Setting yourself for any sort of negative reaction is flat out bad marketing. These companies are smarter than that.

Sheesh!!

Looking at the undercurrent of pure anger and hatred in some comments, one would think You'd attacked their "religion" a thing that I find waay more scary than weird sounds. It's almost as if I am seeing some freaky religion taking shape on the spot.

Fyi, I live close to some old salt-mines, and know of the rumbling we sometimes hear(and feel) tiny earthquakes, when some rock/clay layers settle above these spaces, despite the water thay is injected, cool sounds, but nothing special. Same goes for the giant harbour-cranes a bit further away. They make great, howling kinds of sounds, but, again, nothing special, and outside of some dubious conspiracy-sites, the more eerie sounds(not the rumbling) are not mentioned anywhere.

On ME3 yeah, the moment You mentioned the game, it clicked. The groaning, rattling metal sounds are blatant copies from ME3 sounds, f.i. The ones heard in the end-level, and the moment the Horizon-thing goes bad for the reaper.