Depois de gravar o vídeo, preciso editar o áudio e conferir se a apresentação ficou clara.

Because Portuguese often uses depois de + infinitive when the subject is understood from context.

So:

• Depois de gravar o vídeo = After recording the video / After I record the video

The subject is not stated, but it is understood to be the same person as in preciso: I need.

If you want to state the subject explicitly, Portuguese can also say:

• Depois de eu gravar o vídeo...

That version is more explicit, but the shorter depois de gravar is very common.

Because depois normally combines with de before a noun or an infinitive.

Examples:

• depois de gravar
• depois do almoço
• depois da reunião

So depois de is the standard structure for after in this kind of sentence.

It is in the infinitive because it follows depois de.

In Portuguese, after many prepositions, a verb stays in the infinitive:

• antes de sair = before leaving
• sem estudar = without studying
• depois de gravar = after recording

So gravar is not conjugated here because it is part of the prepositional phrase depois de gravar.

Portuguese often omits subject pronouns when the verb ending already makes the subject clear.

• preciso already means I need
• precisa could mean he/she/you need

So eu is not necessary here.

Portuguese does this much more often than English. Adding eu is possible, but usually only for emphasis, contrast, or clarity.

Portuguese uses definite articles more often than English.

So where English might say:

• record video
• edit audio
• check whether the presentation was clear

Portuguese naturally says:

• gravar o vídeo
• editar o áudio
• a apresentação

This does not always mean the in a strongly specific sense the way it does in English. Very often, the article just sounds natural in Portuguese.

Here conferir means something like:

• to check
• to verify
• to make sure

So conferir se a apresentação ficou clara means checking whether the presentation ended up being clear.

Depending on context, conferir can also mean other things, such as:

• to compare
• to inspect
• to verify information

But in this sentence, check/make sure is the best idea.

Here se means whether / if.

So:

• conferir se a apresentação ficou clara = check whether the presentation was clear

This se is not reflexive here. It is a conjunction introducing an indirect yes/no question.

Compare:

• Não sei se ele vem. = I don’t know if/whether he is coming.
• Vou ver se está certo. = I’ll see if it’s correct.

Because clara agrees with a apresentação, which is feminine.

• a apresentação = feminine singular
• so the adjective must also be feminine singular: clara

Compare:

• O vídeo ficou claro.
• A apresentação ficou clara.

This kind of adjective agreement is very important in Portuguese.

Ficou clara suggests a resulting state: the presentation turned out clear, ended up clear, or came across clearly after being made or reviewed.

Foi clara simply says it was clear.

So the difference is subtle:

• foi clara = it was clear
• ficou clara = it became/turned out clear, with a sense of result

In this sentence, ficou clara works well because the speaker is checking the final result of the presentation.

Yes, but the meaning changes a little.

• ficou clara focuses on the final outcome after preparation or recording
• está clara focuses on its current state right now

So:

• conferir se a apresentação ficou clara = check whether the presentation turned out clear
• conferir se a apresentação está clara = check whether the presentation is clear now

Both are possible in real life, but ficou clara sounds very natural when evaluating the result of something you just made.

The comma separates the introductory phrase from the main clause.

• Depois de gravar o vídeo, = introductory time phrase
• preciso editar... = main clause

This is similar to English writing:

• After recording the video, I need to edit the audio...

In Portuguese, this comma is very normal and helps readability.

Yes. Gravar is a very common verb with more than one meaning.

It can mean:

• to record audio/video
• to save a file
• to engrave in some contexts

In this sentence, because of o vídeo, it clearly means to record.

Examples:

• gravar um vídeo = record a video
• gravar o arquivo = save the file

Both words have written accent marks because the stress does not fall in the most predictable place.

• vídeo → stress on ví
• áudio → stress on áu

Approximate pronunciation in Brazilian Portuguese:

• vídeo ≈ VEE-dee-oh
• áudio ≈ OW-dee-oh or AHW-dee-oh

The accent mark shows the stressed syllable:

• ví-de-o
• áu-di-o

Yes. After preciso, the sentence has two actions the speaker needs to do:

• editar o áudio
• conferir se a apresentação ficou clara

So the structure is:

• preciso + infinitive + e + infinitive

In other words:

• I need to edit the audio and check whether the presentation turned out clear.

This is very common in Portuguese.

You may see it written that way informally, but the comma is preferred in standard writing because Depois de gravar o vídeo is an introductory adverbial phrase.

So the recommended version is:

• Depois de gravar o vídeo, preciso editar o áudio...

It is clearer and more natural in careful writing.

It is singular because the sentence is talking about one presentation.

• a apresentação = the presentation

If there were several, it would change to plural, and the adjective would also change:

• as apresentações ficaram claras = the presentations turned out clear

Notice the agreement:

• singular: a apresentação ficou clara
• plural: as apresentações ficaram claras