I would argue that the behaviors you saw in these are not altruistic.
Baboons will aggressively defend their territories against predators. For example, watch this baboon chase a female lion.
The baboon eventually loses but only when the lion gets help. I'd say the baboons were just chasing away the cheetah and the hyenas as a matter of self defense. The antelope just got lucky.
The same applies for the elephant. It doesn't really approach the buffalo and lion. The lion runs off soon after the elephant arrives in the area. Elephants will also aggressively chase off predators likelions. The lions are right to be afraid.
Same applies for the hippos. They can be aggressive towards crocodiles.
As for the hippo "saving" the wildebeest, we always have to be careful about interpretation. Just because it looks like the hippo was trying to save the life of the wildebeest does not mean that it was the hippo was actually doing. For example, it may have simply been trying to remove the wildebeest from its territory. At times, the hippo puts its mouth around the wildebeest. Was it considering taking a bite? Was it trying to prod the wildebeest? Was it trying to play with the wildebeest?
It's very difficult to demonstrate that any of the behaviors in the videos were displays of altruism.