Yawn...
First - I don't know where this took place. The country that owns the airspace is important context.
Next - the video was shot from inside the airplane. That's one perspective. But it doesn't show the whole situation. F-15s don't intercept as singles. There is always a wingman. So, where was the wingman?
Likely about 3000' behind the airliner. In perfect firing position. Able to sort between the airliner, or either SU-27, who wouldn't have time to react before missile impact. An AIM-9 lock for example, will provide no indication in the cockpit of the SU-27, and the AIM-9 will have no trouble maintaining a precise lock in this instance. From trigger squeeze to impact would be about a second at that range, and the pilot who is flying close formation on the airliner can't see behind him. He has to be maneuvering to see an IR missile launch.
The SU-27s are positioned for a show of force to the people inside the airliner. They feel "protected" by the big fighters in parade formation, close aboard on their wing, but that position is a huge tactical disadvantage for the fighters. They're in no position to maneuver, monitor sensors/weapons, defend, or engage an enemy.
The F-15, similarly, showed up in close parade position, just to let everyone know that the Eagles were there. So, while the fighter lead was close aboard, the wingman was in a tactically relevant, very advantageous, firing position.
It's like this: three bad guys are walking down the street. Not looking behind them. Two cops show up. One walks up to them, and they act tough...but what they don't see is the second cop, right behind them, with his rifle sighted in on the VIP's head... so, while they're acting tough...they're in a completely defenseless position...
The SU-27 didn't "push" anything. He maneuvered aggressively to try and intimidate. The Eagle moved out of his way, in a rational, non-confrontational manner, because his mission was to escort, not start a fight.
IF a fight had started (and no one really wanted it to, but if) the first indication to our video-taker would be the exploding SU-27 on their wing, followed in quick succession by the downing of the second SU-27, who would suddenly be fighting against both Eagles, with one Eagle in a perfect firing position. 2 against 1 with one of the two ready to take a shot.
Not a great way to start a fight
Whenever you see a single US fighter, your first question should always be, "where is his wingman?"