Какой бы фильм мы ни посмотрели, мы всё равно обсудим его в чате.

This is a very common Russian pattern meaning no matter what / whichever.

So:

Какой бы фильм мы ни посмотрели
= Whatever film we watch / No matter which film we watch

The whole sentence means that the choice of film does not affect the result: we will discuss it in the chat anyway.

This pattern is often built like this:

• какой бы ... ни
• кто бы ... ни
• где бы ... ни
• когда бы ... ни

Examples:

• Куда бы мы ни поехали, будет интересно.
  = No matter where we go, it will be interesting.
• Кто бы ни пришёл, я помогу.
  = Whoever comes, I will help.

They work together as part of this fixed concessive pattern.

• бы adds a hypothetical/indefinite sense: whatever / whichever
• ни reinforces the meaning no matter ...

So какой бы ... ни is not random; it is a set structure.

Compare:

• Какой фильм мы посмотрели?
  = Which film did we watch?
• Какой бы фильм мы ни посмотрели...
  = Whatever film we watch...

Without this full pattern, the meaning changes or the sentence sounds incomplete.

This is one of the trickiest things for English speakers.

In Russian, after бы, the verb often appears in the past tense form, but the meaning is not necessarily past. In this structure, посмотрели does not mean simple past we watched. It is part of a hypothetical or generalized idea:

Какой бы фильм мы ни посмотрели...
literally something like: Whatever film we were to watch...

So the form is past, but the meaning is closer to:

• whatever film we watch
• whatever film we may watch
• no matter which film we end up watching

This is normal Russian grammar.

Because the sentence refers to watching a film as a completed event.

• смотреть = to watch, be watching (imperfective)
• посмотреть = to watch and finish / view once (perfective)

A film is usually thought of as something you watch from start to finish, so посмотреть фильм is very natural.

Here the idea is: whichever film we end up watching (to completion), we will discuss it

If you used смотрели, the sentence would sound less natural here, because it would focus more on the process rather than the completed choice/event.

Because фильм is the direct object of посмотреть, and in this sentence it appears in the form expected for an inanimate masculine noun: accusative singular, which looks the same as the nominative.

For masculine inanimate nouns:

• nominative: фильм
• accusative: фильм

So:

• Какой фильм? = Which film?
• Посмотреть какой фильм? = Watch which film?

That is why you see: Какой бы фильм мы ни посмотрели

If the noun were feminine, you would see the difference more clearly:

• Какая бы книга ...
• Какую бы книгу мы ни прочитали...

Его means it here, referring back to фильм.

After обсудим (we will discuss), Russian needs a direct object in the accusative case. For он / фильм, the accusative form is его.

So:

• фильм = the film
• обсудим его = we will discuss it

Russian often uses pronouns this way to avoid repeating the noun:

• Мы посмотрим фильм. Потом обсудим его. = We’ll watch a film. Then we’ll discuss it.

Всё равно means anyway, all the same, or regardless.

It emphasizes that the second part will happen no matter what happens in the first part.

So:

мы всё равно обсудим его в чате
= we’ll discuss it in the chat anyway

Without всё равно, the sentence would still make sense:

• Какой бы фильм мы ни посмотрели, мы обсудим его в чате.

But всё равно makes the idea stronger:

• the choice of film does not matter
• the discussion is guaranteed

Not exactly. It is closer to a concessive sentence than a normal if sentence.

A normal conditional would be:

• Если мы посмотрим этот фильм, мы обсудим его. = If we watch this film, we will discuss it.

But here the meaning is:

• regardless of which film we watch, the result is the same

So it is more like:

• Whatever film we watch, we’ll discuss it
• No matter which film we watch, we’ll discuss it

The key idea is not a condition that may or may not be met, but that different possible choices do not change the outcome.

Because it describes the action that will happen after the film is watched.

обсудим is the future form of the perfective verb обсудить:

• обсудить = to discuss something fully / reach a complete discussion
• обсудим = we will discuss

Perfective future is very common when Russian talks about a single completed future action.

So:

• посмотрели = whichever film we may watch
• обсудим = we will discuss it

Yes, Russian word order is flexible, but the original order is natural and clear.

Original: Какой бы фильм мы ни посмотрели, мы всё равно обсудим его в чате.

You could also hear:

• Какой бы фильм мы ни посмотрели, всё равно обсудим его в чате.
• Мы всё равно обсудим в чате какой бы фильм мы ни посмотрели — possible in some contexts, but much less natural here

The usual order keeps the concessive clause first and the main result second. That makes the logic easy to follow:

1. no matter what film we watch
2. we’ll discuss it anyway

В чате is prepositional case after в, because it means in the chat.

• чат = chat
• в чате = in the chat

This is the normal pattern for location:

• в доме = in the house
• в школе = at school / in the school
• в чате = in the chat

Here it means the place or medium where the discussion happens: we’ll discuss it in the chat

Yes, very often. This is a productive pattern in Russian.

Some common examples:

• Кто бы ни пришёл, я помогу.
  = Whoever comes, I’ll help.
• Где бы мы ни были, мы думаем о доме.
  = Wherever we are, we think about home.
• Когда бы он ни позвонил, я отвечу.
  = Whenever he calls, I’ll answer.
• Что бы ты ни сказал, я не поверю.
  = Whatever you say, I won’t believe it.

So your sentence is one example of a bigger and very useful grammar pattern: interrogative word + бы + ... + ни + verb
meaning no matter / whatever / whoever / wherever / whenever.