Or...one guy shot 3 people, one of which survived, then shot himself.
As for the lack of movie/TV/video game blood splatter, it appears that he used a small caliber weapon. The longer video records 14 shots after that short video. Even when he tried to shoot himself in the head he survived long enough to be taken to the hospital. Obviously something like a 9mm that does not leave a huge exit wound and likely does not even go all the way through the body.
You would have to get to .22 to expect those characteristics.
Projectile velocity and shape is more important than caliber. 9mm can be had anywhere from 800 fps to 1300+ fps, and full jacketed vs hollow point, etc.
My gun knowledge is very sparse so I will defer to you on that one. Same concept though, it took almost 20 shots to kill 2 people so obviously not high caliber.
The blood splatter is mostly movie stuff. Bullet wounds I have seen start with a clean hole then drain blood. Any splatter is contained under the clothing. That it true for a high power rifle or a small caliber handgun. I thought it was reported that he used a .40 cal.? That is a fairly large round and would pass through your body. A 9mm. will also punch through unless one is using a deforming round. Many of us who conceal carry use deforming ammo so that the bullet does not go on to hit someone behind the target.