Learn Hardcore Korean: inteoneseseo yeonghwareul bwayo.

Korean often drops the subject when it’s obvious from context. In this sentence, 저 or 나 (“I”) is implied, so it really means “I watch movies on the Internet.” Depending on context it could also imply “we,” “they,” or “you,” but most naturally it’s first-person.

Why is 인터넷 followed by 에서 and not 에?

The particle 에서 marks the location where an action happens. So 인터넷에서 literally means “at/on the Internet,” i.e. the place you’re watching from. In contrast, 에 alone can mean “to” (direction) or “at” (existence), but doesn’t emphasize an ongoing action.

Could I say 인터넷에 영화를 봐요?

Using 에 here would sound off, because you’re not just existing on the Internet—you’re performing the action of watching there. Stick with 인터넷에서 for “watching on the Internet.”

Why is 영화 in the form 영화를?

영화 means “movie.” It’s the direct object of 보다 (“to watch”), so you add the object particle 를. Since 영화 ends in a vowel, the particle is 를, giving 영화를.

Why is the verb 보다 conjugated as 봐요 and not 보아요?

보다 is a ㅗ-irregular verb. When you add -아요, you drop the ㅗ and contract:
보 + 아요 → 봐요.
보아요 is not used in standard Korean.

What does the -요 ending do? Can I drop it?

Adding -요 makes the sentence polite but casual (the “요-form”). You can drop it in very casual speech (인터넷에서 영화를 봐) or switch to a formal ending for business/strangers (인터넷에서 영화를 봅니다).

Can I use 인터넷으로 영화를 봐요 instead? What’s the difference between 에서 and 으로?

Yes. 인터넷으로 uses 으로 to mark the means or method (“by/through the Internet”). It highlights the Internet as the medium. 인터넷에서 highlights the Internet as the place of action. Both are grammatically correct with slightly different focus.

Does 인터넷에서 영화를 봐요 always mean “I watch movies online”?

Generally yes, but because Korean drops pronouns, the actual subject is flexible. It could also mean “we/you/they watch movies on the Internet” if the context makes that clear.