Hippos are aggressive and short tempered beast. they deserve their reputation as Africa's most deadly mammal. At the same time they re cute, especially the young ones, and have been the favourite of many of my clients on safari.
Never get between a hippo and water. The critter will trample you if you are lucky and bite you in half if you are not. That actually happened to a tourist just a few years ago. However such events are rare. On safari when you see hippos they are pretty much doing what you see in this video; grazing, relaxing, spreading their dung about with a brisk tail wag and yawning.