1 - Being disrespected.
- It becomes clear later over this sentence and the next that Alan Sanford is the object of disrespect here, and that it's not disrespecting people in general that makes him mad.
2 - a customer left him
- We need a subject here because later in the sentence there is a reference back to 'the person' and we need to establish which person this is.
3 - took a photo of the person
- It would be unrealistic for AS to ask for and pay someone to take the photo.
- He obviously took the photo himself and so the active is appropriate.
4 - he was fired
- The active here would be confusing as 'they' seems to refer to both the colleagues and the boss, which would be impossible.
- Using the passive also keeps the focus on Sanford, the main focus of the paragraph.
5 - I could have been given
- The subject of the active sentence 'He' would be unclear. It also becomes clear in number 6 that Sanford is the focus of the sentence.
6 - being sacked
- An -ing form is needed after a preposition.
7 - can't be said
- isn't said is not wrong, but makes it sound as if people actively talk about how interesting flipping burgers is (or not)
- can't be said conveys the notion 'if people were to talk about this ... '
8 - to have her video taken
- Reading ahead, a subject (her video) is needed for the verb posted.
- To be videoed would later imply that Jackie is posted rather than her video,
9 - She shouldn't have posted the video.
- The passive here is not incorrect.
- However, if we want to maintain the focus on the colleague (I'm very angry with my colleague) it is better to maintain the colleague as the subject (She).
10 - to be said
- This is a fixed phrase which is almost always in the passive.