Rules of Continuity in filming

Continuity in filming, is a system of cutting used to maintain continuous and clear narrative action, by following a set of rules. Some of the rules include: the 180 degree rule, shot reverse shot, match on action and many others.

The benefits:
 By having these sets of rules, it makes the film/clip have a more flowing structure that looks realistic. By breaking these rules, your video can look disoriented, messy and can confuse the audience.
It can also make it easier to watch the film, without getting drawn back to reality.

The 180 degree rule:

"A rule stating that a camera should be placed somewhere inside 180 degrees on a particular side of the invisible line of a shot containing two people filmed in sequence.  If the camera crosses the line, confusion results for the film viewers, because it makes it look like the people are switching places as one watches the film. "- creative glossary.

This rule is the main, fundamental element to do with filming.  Its very important not to cross " the line of vision"  between the two characters that you are filming. Otherwise, the audience will not be able to make sense of what is going on in the scene.

https://www.youtube.com/watch?v=HdyyuqmCW14

 I found the above clip helpful in interpreting the rule. It gives an example of a man and a women. The man is on the left, and the women is on the right. It explains how the eye line must also match, otherwise the character talking, can look like they are talking to themselves.

Match on action:

"Cutting on action or matching on action refers to film editing and video editing techniques where the editor cuts from one shot to another view that matches the first shot's action. A common example is a man walking up to a door and reaching for the knob."- Wikipedia
 
It is the basic idea that, one shot cuts to another, demonstrating the action of the first shot. It is usually done using two cameras, as it is very difficult to do with one camera, as you have to get the angles, and mise-en-scene the same in each shot.  After filming, in editing you can crop/cut the two shots together.

https://www.youtube.com/watch?v=laUPi7MPOSQ

I found this link useful in presenting the match on action in film. when the lady is turning the pages, we can see the camera has shot the action twice, but has zoomed in on the second time.

Shot Reverse Shot:

Shot reverse shot (or shot/countershot) is a film technique where one character is shown looking at another character (often off-screen), and then the other character is shown looking back at the first character. - Wikipedia

In essence, it is a shot showing what the character is looking at either through a over the shoulder shot or in a point of view. Then followed by a reverse camera shot of the character themselves looking at it, or the other character looking at them for example.
https://www.youtube.com/watch?v=o1Ey0a6LJRA

I found this clip useful, in analysing how the shot reverse shot is used. We can also see the two characters eyelines, which makes the clip to look more realistic.