It isn't like that either. I'll give you an example of what the game is like. One of the races, the Quarians, created a type of VI called the Geth. Eventually, the Geth's adaptive consciousness developed to the point of self-awareness, and the Quarians tried to exterminate them. They failed, and were forced to evacuate their homeworld, Rannoch. The Reaper invasion begins about the same time as the Quarians decide to retake their homeworld. Unfortunately, the Geth decided to ally themselves with the Reapers right after they were attacked, and of course Shepard has to save their asses. Depending on your decisions throughout the last two games, there might be an option to save both the Quarians and the Geth, but it's very difficult to get this lucky combination, unless you look up how to do it ahead of time. If you didn't import your save, or if you made some bad calls, you will have to decide which race will be wiped off the face of the Earth, er... universe.
The first two clips show Shepard communicating with a downed Reaper, but the third doesn't. Interestingly, all three seem to be from people who chose a "renegade" pathway over "paragon" options, judging by the conversation options they selected.
Clip one is saving the Geth and the Quarians, clip two is saving the Geth, and clip three is saving the Quarians. All the clips are less than ten minutes long.
The third clip is from a game where someone didn't import a save file. Either that, Legion didn't survive the suicide mission, or they decided to sell the deactivated Geth to Cerberus.
Your choices impact the scene, of course, but also have a serious impact on what war assets you acquire. if the army you assemble isn't large enough, the mission to retake Earth will fail, and you will be unable to stop the Reapers using the Crucible project.