The expository documentary mode is mainly about the verbal emphasis on the commentary side in a documentary, usually done by narrators. This is achieved by using voiceovers as well as titles which gives has an authoritative tone and effect to which puts the audience under the power of the narrator or sometimes the presenter (especially because this type of mode aims for the narrator/presenter to talk directly to the audience) hence why the expository mode is also known as "The voice of God". This mode is commonly used for television news programmes and can also be used in wildlife documentaries as well which the main purpose is to inform and educate the audiences. For example, Steve Backshall documentaries are all about wildlife and he speaks directly to the audience explaining the behaviours and actions being made by the animals which engages the video and has them under his 'authority' which is really an advantage because then what's the purpose of making a documentary? His documentaries are evidentiary; editing which serves to maintain the continuity of the spoken perspective by combining shots together showing different shots (close ups and long shots) in order to show the subject as well as the surroundings to also emphasise the events that occur.
If you have a look at this documentary by Steve Backshall the beginning begins with a close up/zoom into a tigers foot in order for the audience to see the animal he would be studying in that documentary(voiceover).
The disadvantage with the expository mode is that it might seem subjective as it's coming from the narrator or the presenter view and perspective but this mode is mainly used for factual documentary where the narrator/presenter is impartial and use evidence besides facts.
The observational documentary mode is also known as the "window on the world" as it persist of social actors who behave as if no film maker is present and they are living a normal life. This means there's no voiceovers, no soundtrack, no narrators, sometimes no interview; basically the only type of sound you'll hear is dialogue (diegetic sound) and whatever sound the actors decide to play but not done during the editing process. Examples i can use for this mode is the "Keeping up with the Kardashian" show or "The Osbournes" which is about famous families lives and keeping up with what they do daily.
The main advantage of this mode is that nothing is planned (well for most of it) so it is up to the audience to explore the issues and events which can be said to engage viewers. However, there will be some bits/scenes where the audience will not understand what is going on but the actors do which can and/or may disengage the viewers and can be off-putting. The actors also tend to not repeat certain things again so if you miss it, that's it.
Looking at the video below you can see that there is camera's everywhere the actors go which also shows continuity and can be done by in camera editing but for this show there is too many movement and locations for it to be in-camera editing, the only explanation is combining shots especially because it's multi-cam. The actors also avoid looking at the camera which adds to the effect of the documentary to be the window on the world.
The participatory documentary mode is often indicated by an interview between the film makers and the subject. This means the audience gets to perceive sometimes personal interviews. It is most effective with criminal 'judgement' documentaries an example of this is "Aileen Wuornos; Life and Death of a serial killer" by Nick Broomsfield. Nick Broomsfield being the film maker had an opportunity to interview Aileen in person which was shown like an old footage (archival footage) and we audience can tell that she is mentally ill and not in the right state of mind hence why she kills people. I'd say that this documentary is objective to an extent as we actually get information and we hear from both sides, the government and the criminal herself. However, the documentary being based on her and I think the motive was to make the audience feel a certain way about her as well as the fact that this documentary is basically Broomsfield's response. So we are not meant to like her.
The reflexive documentary mode allows the audience to know that is actually a documentary all throughout by the film maker showing the 'behind the scenes' and making the audience opinions matter. An example of a documentary which implemented this mode is called "Stories we tell" which was actually about stories we do tell during our life time. This meant the documentary consisted of this family's old footages and baby pictures in order to reflect on them. This is very effective on audiences as it sort of indicates that everything stated is true and emphasises on actually telling a story; especially the voice-overs used over the old pictures and clips which described the events and what is happening in the picture/s. Soundtracks were also effective as they synchronised/ matched what was going on. For example, there was sound music in scenes where emotions are meant to be felt.
The performative documentary mode is normally based on someones personal experience usually the film maker; you can say that it is subjective as the audiences are being forced to believe something and calls for an emotional response that acknowledges an understanding events and occurences. The main purpose of documentaries like this is to educate the audience (example of film gratification). An example of performative documentary is Catfish which is about people who have been in relationships with the wrong people or the person they thought it was but it wasn't. This had happened to Ariel Schulman and Henry Joost, the film makers. If you have a look at the documentary, the commentary comes from the two men and then they show the people who are being catfished. A hand held camera is used when going to meet the person who is catfishing this is noticeable by the jerkiness of the camera. It can be concluded that the camera is hidden too as when they do meet the 'pretenders' they don't want them to know they're being filmed just for that realism and to make the audience believe that they are actually bad people and the whole idea is wrong.