I'm a filmmaker so I could go on and on about this. But I won't. Just let me say this. Stills are awesome reminders of your trip. I shoot thousands. I have a gallery. But video takes you back there.
Watching these animals move is awesome. And watching them move in slow motion is even more awesome. So use that function on your camera. Just don't be like my dad who shot his entire Alaskan vacation in video and made us watch it all. That was painful. Steady your camera and keep your clips short... but not too short. Give your audience a chance to absorb the fascination. DON'T zoom during the shot. Do that before or after (you don't see zooms in the movies you go to at home so don't do it here... it draws attention to the camera). Don't try too hard to follow everything. Even though it looks steady to you through the viewfinder it's probably bouncing around a bit. Calm that down. Don't be afraid to let the animal walk in and out of frame. Try not to talk when you shoot unless you have something relevant to say... you're going to hear it later. Let Africa do the talking. Shoot slow motion. You'll love the results. Practice before you go. And as always, hit the "ASK JEFF" button if you need advice.