This video show defenses against side and front kicks. Side and front kicks are straight, thrusted kicks, that's why you escape to one side instead of hopping backwards. Roundhouse kicks on the other side are circular kicks and therefore, defense techniques are different.

1. Escape to the left or the right and block the kick with your arm ( see video ). Then counter attack or just keep going.
2. You can also grab your opponents leg and throw or sweep him.
3. If your opponent kicks head height, you can't grab his leg, but you can still block and counter-attack or apply another throw ( where your don't grab the foot ).