Questions & Answers about Mój brat niedawno widział ten film.
Why does the verb widzieć (to see) become widział here?
This is the past tense for a masculine singular subject. Because mój brat (my brother) is male, we use the masculine past tense ending -ł. Notice that verbs ending in -eć like widzieć usually change their e to an a before this masculine ending, making it widział. If the subject were female, it would be widziała.
Why did ten film (this movie) keep its basic ending? Isn't it the object of the sentence?
You are right that it is the direct object, so it is in the accusative case. However, film is a masculine inanimate noun (a thing, not a person or animal). In Polish, masculine inanimate nouns and their adjectives like ten look exactly the same in the accusative case as they do in the basic nominative case.
How does the word niedawno translate to recently?
It is made up of two parts: nie (not) and dawno (a long time ago). So it literally translates to not a long time ago, which is the exact same concept as recently.
Why do we use mój for my instead of moja or moje?