Learn Hardcore Japanese: ane wa douga o tsukurimasu.

Because は marks the topic of the sentence, not necessarily the grammatical subject. Here it tells us “As for my older sister…,” setting her up as the context. If you used が, it would instead emphasize or introduce 姉 as new information.

What role does を play in 動画を作ります?

The particle を marks the direct object of the verb. It links 動画 (the thing being made) to 作ります (the action of making), so you literally have “(topic) older sister – video – makes.”

What exactly does 動画 mean?

動画 refers to a video clip or moving image, often used for digital or online content (for example, YouTube videos). It’s not the same as 映画 (movie); it’s usually shorter, user-generated content.

Why is the verb 作ります used here instead of します?

作る (作ります in polite form) means “to make” or “to create.” You “make videos” (動画を作る). Using する (to do) with 動画 would sound unnatural, because you’re not “doing a video” but rather “creating” one.

Does 作ります indicate present tense, future tense, or something else?

Japanese present tense (dictionary or ます form) covers both habitual actions and future plans. In this sentence it most naturally means a habitual action: “My older sister makes videos (regularly).” Context could also allow “will make videos.”

Why isn’t there a word for “my” before 姉?

In Japanese, kinship terms like 姉 inherently imply “my older sister” when spoken by the person to whom she belongs. Adding 私の姉 is grammatically correct but often redundant in casual speech.

What is the typical word order in this sentence?

Japanese follows Subject-Object-Verb (SOV) order. Here it’s:
Subject/Topic: 姉は
Object: 動画を
Verb: 作ります

If I talk about someone else’s sister, should I still use 姉?

No. When referring to another person’s older sister, you use the honorific form お姉さん. Using plain 姉 for someone else’s sister sounds odd or too familiar.