Learn Hardcore Polish: W weekend wybieram inny film. - On the weekend I choose a different movie.

Weekend in the accusative is the same form as the nominative (weekend), so w weekend is correct and natural for “on the weekend”.
W weekendzie is possible but sounds unusual; you will almost never hear it in everyday speech in this meaning.

Does w weekend mean “at the weekend” or “on the weekend”? Is there any difference from English?

W weekend can correspond to both English “at the weekend” (BrE) and “on the weekend” (AmE). It simply means “during the weekend / over the weekend”.

Examples:

W weekend pracuję. – I work at/on the weekend.
W weekend jadę do rodziców. – I’m going to my parents’ over the weekend.

The Polish phrase doesn’t distinguish between British and American style; it’s just a neutral time expression.

Why is the verb wybieram (present tense) used if the sentence is about the future (the weekend)?

In Polish, the present tense of an imperfective verb (like wybierać) is very often used to talk about the near future, especially when there is a clear future time expression in the sentence.

So:

W weekend wybieram inny film.
Literally: On the weekend I choose a different film,
but functionally: I’m choosing / I’ll choose a different film (this weekend).

It’s similar to English:

I’m choosing a different film this weekend.

Because we already have w weekend, the time is clearly future, so Polish doesn’t need a special future form here.

What is the difference between wybieram and wybiorę in this sentence?

Both can talk about the future, but the nuance is different:

W weekend wybieram inny film.
– imperfective (wybierać)
– sounds like a plan / arrangement, or a habitual action
– can be understood as: This weekend, I’m going to be choosing / I pick another film.
W weekend wybiorę inny film.
– perfective (wybrać)
– focuses on the single completed act of choosing
– more like: Over the weekend I will make the choice of a different film (once).

In many everyday contexts, both are possible; wybiorę sounds more like a one‑off, completed decision.

Could I say będę wybierać inny film instead of wybieram inny film?

Yes, but it sounds a bit more emphasized / prolonged and less natural in this very short sentence.

W weekend będę wybierać inny film.
Literally: On the weekend I will be choosing a different film (for some time).

This form (będę + imperfective infinitive) often suggests an ongoing or repeated future activity, or you use it if you really want to underline the future grammatically.

For a simple future plan, W weekend wybieram inny film is shorter and more common.

Why is it inny film and not inna film or inne film?

The adjective must agree in gender, number, and case with the noun.

film is masculine singular (and here in the accusative case).
The correct masculine singular accusative form of inny is inny.

So:

inny film – a different film (masculine singular)
inna książka – a different book (feminine singular)
inne miasto – a different city (neuter singular)
inne filmy – different films (plural)

Because wybierać takes a direct object in the accusative, inny film here is also in the accusative. For masculine inanimate nouns like film, the accusative form looks the same as the nominative, so it doesn’t change shape.

What exactly does inny mean here? Is it “another”, “different”, or “new”?

In this context inny means “different” or “another (different)”:

W weekend wybieram inny film.
– I’m choosing a different film (not the one we had before / not the usual one).

Some useful contrasts:

inny film – a different film
jeszcze jeden film – one more film (an additional one)
kolejny film – the next film (in a sequence)
nowy film – a new film (not used before / newly released, depending on context)

So if the key idea is “not the same as before”, inny is the right word.

Why is there no word for “a” in inny film? How do articles work in Polish?

Polish has no articles (a, an, the). The noun phrase:

inny film

can mean:

a different film
the different film (depending on context)

The specificity (whether it’s “a” or “the”) is given only by context, not by a separate word. If you need to be very explicit, you add more detail:

ten inny film – literally this different film, often functioning like that different film / the different film.
jakiś inny film – some different film / some other film.

Can I change the word order, e.g. Wybieram inny film w weekend? Does it change the meaning?

Yes, Polish word order is flexible, and all of these are grammatically correct:

W weekend wybieram inny film.
Wybieram inny film w weekend.

The basic meaning stays the same. Differences:

The original W weekend wybieram inny film slightly emphasizes the time (“At the weekend, I’m choosing a different film”).
Wybieram inny film w weekend sounds a bit more neutral or spoken, like a simple statement where the action comes first.

In ordinary conversation, both will be understood the same way; the difference is subtle.

If I mean every weekend I choose a different film, how would I say that?

You would pluralize weekend and often adjust the object:

W weekendy wybieram inne filmy.
– On/at weekends I choose different films.

Other natural options:

W każdy weekend wybieram inny film.
– Every weekend I choose a different film.
W weekendy zawsze wybieram inny film.
– On weekends I always choose a different film.

Note: weekendy is the plural form of weekend.

Is wybierać the usual verb for “choose a film”, or would Poles say something else?

Yes, wybierać / wybrać is the standard verb for choosing among options:

W weekend wybieram inny film. – I’m choosing a different film.
Musimy wybrać film. – We need to choose a film.

Other verbs you might hear:

zdecydować się na film – to decide on a film
wytypować film – to pick/select a film (more formal / specific contexts)

But for everyday “choosing which movie to watch”, wybierać film is perfectly natural.