É melhor que você salve o vídeo antes de desligar o computador.

Because é melhor que is followed by the subjunctive.

So the pattern is:

• É melhor que + [subjunctive]

The verb salvar in the present subjunctive for você/ele/ela is salve.

Examples:

• É importante que você estude.
• É bom que ele chegue cedo.
• É melhor que você salve o vídeo.

If you used salvar, you would need a different structure, such as:

• É melhor você salvar o vídeo...

And salva is the present indicative, which does not fit after é melhor que in this sentence.

Here, que introduces a subordinate clause, similar to that in English, although English often leaves that out.

Structure:

• É melhor que você salve o vídeo...
• literally: It’s better that you save the video...

In Portuguese, this que is required in this kind of structure when a full clause follows.

Compare:

• É melhor que você salve o vídeo.
  = It’s better that you save the video.

• É melhor salvar o vídeo.
  = It’s better to save the video.

• É melhor você salvar o vídeo.
  = a very common Brazilian structure, more like You’d better save the video.

Yes. That is very common in Brazilian Portuguese.

Both are natural:

• É melhor que você salve o vídeo antes de desligar o computador.
• É melhor você salvar o vídeo antes de desligar o computador.

The version with que + subjunctive sounds a bit more grammatically explicit and sometimes slightly more formal or careful.

The version with você + infinitive is extremely common in everyday Brazilian speech and often sounds very natural.

Because você takes third-person singular verb forms in Portuguese.

So although você means you, the verb behaves like he/she grammatically.

Examples:

• você fala
• você quer
• você pode
• que você salve

That is why you get:

• você salve, not você saves in an English-like sense, and not a separate second-person form.

Because antes de + infinitive is the normal structure when the subject is the same or understood from context.

Here, the person who saves the video is also the person who turns off the computer, so antes de desligar works perfectly.

Structure:

• antes de + infinitive

Examples:

• Lave as mãos antes de comer.
• Feche o arquivo antes de sair.
• Salve o vídeo antes de desligar o computador.

You can also use antes que + subjunctive, but that structure is more typical when the action is presented as a separate clause, often with a clearer or different subject:

• É melhor que você salve o vídeo antes que o computador desligue.

That means something different: before the computer shuts down.

Portuguese uses definite articles more often than English.

In this sentence, o vídeo and o computador refer to specific things in the situation: the video you are working on and the computer you are using.

So Portuguese naturally says:

• salvar o vídeo
• desligar o computador

Even where English might say save the video and turn off the computer, Portuguese almost always keeps the article.

This is very normal and something English speakers need to get used to.

Sometimes yes, but in this sentence keeping você is helpful and natural.

Portuguese often drops subject pronouns, but salve could refer to:

• você
• ele
• ela
• o senhor / a senhora

So if you remove você, the sentence may become less clear out of context:

• É melhor que salve o vídeo antes de desligar o computador.

That can still work in context, but it is less clear than:

• É melhor que você salve o vídeo antes de desligar o computador.

In Brazilian Portuguese, subject pronouns are used quite a lot anyway, so keeping você sounds very normal.

Yes.

Desligar means to turn off, to switch off, or for a computer, often to shut down.

Examples:

• desligar a luz = turn off the light
• desligar a TV = turn off the TV
• desligar o computador = turn off / shut down the computer

It is the natural verb here. You would not normally use apagar for turning off a computer in this sense.

Yes.

• É needs the accent because it is the verb ser in the form is.
• vídeo needs the accent because of its stress pattern.

In writing, these accents matter and are considered standard spelling.

So write:

• É melhor...
• o vídeo

not:

• E melhor...
• o video

In some parts of Brazil, yes, but the verb form may change depending on the region and speaking style.

More traditional grammar:

• É melhor que tu salves o vídeo antes de desligar o computador.

In many Brazilian varieties, people use tu but still use third-person verb forms in everyday speech:

• É melhor que tu salve o vídeo...

That depends heavily on region.

If you are learning general Brazilian Portuguese, você is the safest and most widely useful choice.

It is an expression of advice, recommendation, or judgment.

Portuguese often uses the subjunctive after expressions like:

• É bom que...
• É importante que...
• É melhor que...
• É necessário que...

These expressions do not simply describe facts; they express what is advisable, desirable, or necessary. That is why the subjunctive appears.

So in your sentence, É melhor que você salve... is not just stating an action; it is recommending it.