Титры идут под саундтрек.

In Russian, идти is often used much more broadly than English to go or to walk.

Here идут means something like:

• are playing
• are running
• are appearing
• are rolling

So Титры идут can mean the credits are rolling / the credits are on screen.

This is a very common extension of идти in Russian. For example:

• Фильм идёт в кинотеатре = The film is showing at the cinema
• Дождь идёт = It is raining
• Часы идут = The clock is running

So in this sentence, идут is idiomatic.

Титры is normally used as a plural noun when talking about film or TV credits, and sometimes on-screen text.

So Russian treats credits here much like English does: the idea is naturally plural.

Compare:

• титр = a single title card or caption
• титры = credits / titles as a whole

That is why the verb is also plural:

• титры идут
• not титры идёт

In this sentence, под means to the accompaniment of, with, or against the background of.

So под саундтрек suggests that the credits are going/rolling with the soundtrack playing.

This use of под is common in Russian. It often describes something happening while some music or sound is playing:

• танцевать под музыку = to dance to music
• петь под гитару = to sing to guitar accompaniment
• засыпать под дождь = to fall asleep to the sound of rain

So идут под саундтрек means the credits appear while the soundtrack is playing.

Here под takes the accusative case because it means to the accompaniment of.

The noun саундтрек is masculine and inanimate, and for masculine inanimate nouns, the accusative singular is the same as the nominative singular:

• nominative: саундтрек
• accusative: саундтрек

So the form does not change, even though it is in the accusative.

This can be confusing for learners because the case is there grammatically, but the word looks unchanged.

Yes. Под can take either the accusative or the instrumental, depending on meaning.

Very roughly:

• под + accusative often suggests direction, result, or accompaniment in certain expressions
• под + instrumental often means under in a static physical sense

Examples:

• положить книгу под стол = to put a book under the table
  movement toward a position under the table, so accusative

• книга лежит под столом = the book is lying under the table
  location, so instrumental

In your sentence, под саундтрек is not physical under. It means to the soundtrack / with the soundtrack playing, so this is a different idiomatic use.

That depends on context.

Титры can refer to:

• credits
• titles
• sometimes general on-screen text

But subtitles are more specifically субтитры.

So if the meaning shown to the learner is credits, that is perfectly natural. In film language, титры often means the opening or closing credits.

A useful distinction:

• титры = credits / titles
• субтитры = subtitles

It is a loanword from English, but it is fully normal in modern Russian, especially in conversations about films, TV, and music.

It behaves like a regular masculine noun:

• саундтрек
• саундтрека
• саундтреку
• etc.

Russian also has more native or less directly borrowed alternatives depending on context, such as:

• музыка
• звуковая дорожка

But саундтрек is very common and natural.

Yes. Russian word order is flexible, though changing it can shift emphasis.

The basic sentence is:

• Титры идут под саундтрек.

You could also say:

• Под саундтрек идут титры.

This version puts more focus on под саундтрек, as if emphasizing the soundtrack first.

The original order is neutral and natural.

Yes. They overlap a little, but they are not identical.

• идут sounds idiomatic for something that is running / rolling / being shown
• показываются means are being shown / are appearing

So:

• Титры идут = The credits are rolling
• Титры показываются = The credits are being shown

The first one is more natural if you want the usual film-style idea of credits rolling with music.

A rough pronunciation guide is:

TEE-try ee-DOOT pot SOUN-dtrek

A few details:

• Титры = stress on the first syllable: ТИтры
• идут = stress on the last syllable: иДУТ
• под is pronounced close to pot because the final д is devoiced
• саундтрек usually has stress on саунд: САУНДтрек

If you want to sound more natural, the main sentence stress will often fall on идут or саундтрек, depending on what you want to emphasize.

Yes, very often.

This pattern is productive and useful:

• сцена идёт под музыку = the scene plays with music
• реклама идёт под весёлую мелодию = the ad runs to a cheerful tune
• видео идёт под комментарий автора = the video plays with the author’s commentary

So идти под + sound/music is a common way to describe something unfolding while a soundtrack or other audio accompaniment is playing.