Ever wonder why Scar became evil??
It is because of the Horrible characteristic of every Lion!!!
it is because if other Lion killed the alpha Lion of the pride they will also kill all the cubs so that their own lineage will rule and to secure that no one will ever protest on how they rule..
just like the one in the video
so we can say that Mufasa's dad killed Scar father the original Alpha of the pride and Scar just Survived the horrible Slaughtering of Mufasa's dad to all of his brothers and that is how he got his Scar and why he wants to kill Mufasa and Simba so Badly....