Learn Hardcore Turkish: Filmi baştan sona izledim. - I watched the film from start to finish.

Filmi izledim. = I watched the film (the one we both know).
Bir film izledim. = I watched a film (unspecified). Using the accusative on an indefinite object is generally not done; bir filmi implies a specific “one film (in particular).”

Could filmi also mean “his/her film”?

Yes, context decides. Filmi can mean either “the film” (accusative) or “his/her film” (3rd-person possessive). To disambiguate:

“the film”: O filmi izledim. (I watched that film.)
“his/her film”: Onun filmini izledim.

How is filmi formed? Why no buffer -y?

Accusative is -ı/-i/-u/-ü by vowel harmony. film ends with a consonant, so add the suffix directly: film + i → filmi. The buffer -y (as in arabayı) is only used when the noun ends in a vowel. More examples:

kitap + ı → kitabı (p→b softening)
okul + u → okulu
gül + ü → gülü

What does baştan sona literally mean, and which cases are used?

Literally “from the beginning to the end.”

baştan = baş (beginning) + ablative -DAn → devoiced after a voiceless consonant: -tan
sona = son (end) + dative -A It’s a set phrase meaning “from beginning to end / all the way through.”

Is baştan sona kadar correct, or is kadar redundant?

It’s common and acceptable. Kadar means “until/up to” and adds emphasis, but baştan sona already conveys the idea. You’ll also hear baştan sonuna kadar (“from the beginning to its end”), which uses possessive marking on “end.”

Can I say başından sonuna kadar or en başından en sonuna kadar?

Yes. These explicitly mark possession (“its beginning/its end”) and are very natural when the referent (the film) is clear:

Başından sonuna kadar izledim.
En başından en sonuna kadar izledim.

Where can baştan sona go in the sentence? Are other orders okay?

Typical placement is before the verb. All are possible, with slight emphasis differences:

Filmi baştan sona izledim. (neutral)
Baştan sona filmi izledim. (focus on the span)
Filmi izledim baştan sona. (afterthought/emphasis in speech; less formal)

Why is there no subject pronoun? How do I add it?

Turkish drops subject pronouns because they’re encoded on the verb. İzledim already means “I watched.” Add pronouns for emphasis:

Ben filmi baştan sona izledim. (I, not someone else, watched it.)
Filmi baştan sona ben izledim. (Strong focus on “I”.)

What tense/aspect is izledim? Could I use other forms?

İzledim = simple past, completed action. Other common options:

İzliyorum = I’m watching (right now/these days)
İzlemiştim = I had watched
İzlemişim = apparently I watched / I (now realize I) watched (evidential/indirect)

How is izledim built? How do I make negatives and questions?

izle- (watch) + -di (past) + -m (1sg) → izledim
Negative: izle-me-di-m → izlemedim (I didn’t watch)
Yes/no question: add the particle (separate word): izledim mi?; 2sg: izledin mi? The particle harmonizes: mı/mi/mu/mü.

Does izlemek mean the same as seyretmek or bakmak?

izlemek and seyretmek both mean “to watch.” İzlemek is more general/modern; seyretmek can feel a bit more formal or old-fashioned in some regions, but both are fine: Filmi izledim/seyrettim.
bakmak = to look (briefly/direct your eyes): Filme baktım ≈ “I looked at the film” (not “watched” it).
görmek = to see (perceive).

How do I say “I watched a film from beginning to end”?

Use an indefinite object without accusative:

Baştan sona bir film izledim. Placing bir after the adverbial is common. Bir filmi izledim implies “one particular film” (specific selection), not a generic “a film.”

Any pronunciation tips for this sentence?

ş is “sh.” baştan = “bash-tan.”
Many speakers say film as two syllables in casual speech: “fi-lim.” filmi is “fil-mi.”
Dotted i (i/İ) and dotless ı (ı/I) are different sounds. izledim uses dotted i both times.

Do I ever write an apostrophe in filmi?

No. Apostrophes are only for proper names with suffixes: Titanic’i izledim. Common nouns take suffixes without an apostrophe: filmi, okulu, kitabı.