Rotoscoping is the process of tracing over live action video to create an animation. Some animators consider this a lazy way of cheating — and if you are literally just tracing video, that's pretty true. At the same time, this method can be really helpful for animating complicated "3d camera movements" or other challenging actions.
Rotoscoping is most effective when used as just one aspect of an animation. This might be where the rotoscope is used like an underpainting/skeletal structure - or when creating a seamless transition between live action and animation. So when rotoscoping, trace just the information you need and add to it to make something new.
Animation Smears are a way that animators show a sense of increased speed by distorting the form of the moving subject over just a couple frames. There are a few smear techniques. These can be used individually or combined together to really exaggerate the sense of speed.
For this type of smear, an elongated drawing of the subject is placed between the start and end of the movement.
For multiples (sometimes called repeats), either the entire subject (or just part - ie. the legs) are drawn multiple times in different positions.
This literally looks like you have dragged a dry brush through wet paint, so that the marks made by the individual bristles create the sense of speed.