Comprimo il video prima di inviarlo.

Comprimo is the 1st person singular present indicative of comprimere: I compress.

So:

• comprimo = I compress
• base verb: comprimere

This verb is a little irregular in the present tense:

• io comprimo
• tu comprimi
• lui/lei comprime
• noi comprimiamo
• voi comprimete
• loro comprimono

In this sentence, Comprimo il video... means I compress the video...

Italian often omits subject pronouns when they are not needed, because the verb ending already shows who is doing the action.

• Comprimo already means I compress
• so io is optional

You could say:

• Io comprimo il video prima di inviarlo

But usually io is only added for emphasis, contrast, or clarity.

For example:

• Io comprimo il video, tu no. = I compress the video, you don’t.

In Italian, the definite article is used more often than in English.

So il video means:

• the video

Even when English might sometimes say just video in a general or practical context, Italian often keeps the article.

Here, il is used because video is masculine singular:

• il video
• i video (plural)

Also, video is normally invariable in Italian, so the singular and plural noun form stays the same.

Prima di means before when it is followed by a verb.

Pattern:

• prima di + infinitive

So:

• prima di inviarlo = before sending it / before I send it

Examples:

• Prima di uscire, chiudo la finestra. = Before going out, I close the window.
• Prima di mangiare, mi lavo le mani. = Before eating, I wash my hands.

If prima is followed by a full clause with a conjugated verb, Italian usually uses prima che instead:

• Lo comprimo prima che tu lo invii. = I compress it before you send it.

So in your sentence, di is there because the next verb is an infinitive: inviare.

Because object pronouns are usually attached to the end of an infinitive.

• inviare + lo becomes inviarlo

Here, lo means it, referring to il video.

So:

• inviarlo = to send it

This is very common in Italian:

• farlo = to do it
• vederlo = to see it
• mandarlo = to send it
• comprarlo = to buy it

You do not normally say inviare lo in this kind of structure.

Lo is the direct object pronoun meaning it, and it refers to il video.

Since video is masculine singular, the matching direct object pronoun is:

• lo = him/it for masculine singular objects

So the sentence literally works like this:

• Comprimo il video = I compress the video
• prima di inviarlo = before sending it

The -lo avoids repeating il video.

Without the pronoun, you would have:

• Comprimo il video prima di inviare il video.

That is grammatical, but repetitive and unnatural.

Italian often uses the infinitive when the subject of both actions is the same.

In this sentence, the same person does both actions:

• I compress
• I send

So Italian uses:

• prima di + infinitive

That is why you get:

• Comprimo il video prima di inviarlo.

If the subject changes, Italian usually switches to a full clause, often with prima che:

• Comprimo il video prima che Marco lo invii.
• I compress the video before Marco sends it.

So a useful rule is:

• same subject → prima di + infinitive
• different subject → often prima che + conjugated verb

Yes. In English, this Italian sentence can be translated in more than one natural way:

• I compress the video before sending it.
• I compress the video before I send it.

Italian does not need to choose between those two English wordings here. The structure prima di + infinitive naturally covers that idea.

Depending on context, it could describe:

• a habit: I always compress the video before sending it
• a routine step: I compress the video before sending it
• something happening right now / in the near future, depending on context

You could also use mandare in many everyday situations.

For example:

• Comprimo il video prima di mandarlo.

That sounds very natural in spoken Italian.

Very roughly:

• inviare = a bit more formal, technical, or neutral in digital contexts
• mandare = very common, everyday to send

If you are talking about sending a file, message, or email, both can work.
Inviare may sound slightly more formal or more typical in interface/button language, while mandare is often more conversational.

Because the expression is fixed as prima di + infinitive.

Italian prepositions depend a lot on the expression they belong to, and they do not always match English prepositions logically.

So you should learn this as a chunk:

• prima di fare qualcosa = before doing something

Examples:

• prima di uscire
• prima di parlare
• prima di dormire
• prima di inviarlo

Using a or da here would be incorrect.

Usually no. Video is generally treated as invariable.

So:

• il video = the video
• i video = the videos

Examples:

• Comprimo il video.
• Comprimo i video.

This is useful because learners often expect something like vidi or another changed plural form, but standard Italian keeps video the same.

Not in this exact structure.

With an infinitive, the pronoun is normally attached:

• inviarlo = correct

In other structures, object pronouns can go before a conjugated verb:

• Lo invio domani. = I’ll send it tomorrow.
• Lo comprimo subito. = I compress it right away.

But with prima di + infinitive, the natural form is:

• prima di inviarlo

So compare:

• Lo invio dopo. = pronoun before conjugated verb
• prima di inviarlo = pronoun attached to infinitive

The ending pronoun would change to match the direct object.

Examples:

• Comprimo la registrazione prima di inviarla.
  = I compress the recording before sending it.

• Comprimo i file prima di inviarli.
  = I compress the files before sending them.

• Comprimo le immagini prima di inviarle.
  = I compress the images before sending them.

Pronouns used:

• lo = masculine singular
• la = feminine singular
• li = masculine plural
• le = feminine plural

So in your sentence, -lo is used because video is masculine singular.

Yes, absolutely.

Italian word order is flexible, so both are natural:

• Comprimo il video prima di inviarlo.
• Prima di inviarlo, comprimo il video.

The meaning stays the same. The second version simply puts more focus on the time sequence: before sending it.

This kind of fronting is very common in Italian.