ie de douga wo mite bakari iru to, syukudai ga owarimasen.

で marks the place where an action happens.

• 家で = at home
• The action is 動画を見る (to watch videos), and that action happens at home.

If you used に here, it would sound like a destination or existence point instead, which is not what this sentence needs.

Because 動画 is the direct object of 見る.

• 動画を見ます = watch videos
• を marks the thing that the action is done to.

So in this sentence:

• 動画を見て = watching videos

This is a set grammar pattern:

• V-てばかりいる

It means something like:

• to keep doing nothing but V
• to spend all one’s time V-ing
• to be always V-ing

So:

• 見てばかりいる = to do nothing but watch / to keep watching all the time

The て-form is required in this pattern.

Here, ばかり means nothing but, only, or too much of one thing.

But it often has a nuance of complaint, criticism, or imbalance.

So 動画を見てばかりいる does not just mean watch videos. It suggests:

• you are watching videos excessively
• you are watching videos instead of doing other things you should do

That nuance is important.

いる adds the idea of an ongoing or habitual state.

So:

• 見てばかり by itself feels incomplete in many situations
• 見てばかりいる means to be in the state of always watching

It makes the expression sound like a continuing pattern of behavior, not just one single action.

Because clauses before と normally use plain form, even in a polite sentence.

So this is very natural:

• 見てばかりいると、宿題が終わりません。

The first part is a subordinate clause, and subordinate clauses usually stay plain.

This kind of mix is completely normal:

• plain form in the conditional clause
• polite form in the main sentence

Here, と is a conditional, meaning if or when.

But it often has the nuance of a natural, automatic, or predictable result.

So the sentence is not just saying a random possibility. It is more like:

• If you keep doing that, this is what happens
• When you do that, the result is that your homework doesn’t get finished

That makes と a very natural choice here.

Because 終わる is an intransitive verb.

• 終わる = to end / to be finished
• Intransitive verbs usually take が, not を

So:

• 宿題が終わりません = the homework does not get finished / is not finished

If you want を, you would normally use a transitive verb such as 終える:

• 宿題を終えません = I do not finish the homework

The original sentence focuses on the result: the homework remains unfinished.

In Japanese, the non-past form can express:

• present
• future
• habitual/general truth

So 終わりません here means something like:

• won’t get finished
• doesn’t get finished

It is not limited to the present moment. It works well for a general consequence: if you keep watching videos, the homework won’t get done.

Yes, the subject is omitted, which is very common in Japanese.

Depending on context, it could mean:

• you
• I
• one
• some other understood person

English usually needs a subject, but Japanese often leaves it out when it is obvious from the situation.

So the sentence can be understood as something like:

• If you do nothing but watch videos at home, your homework won’t get finished.

But the Japanese itself does not explicitly say you.

It can mean either, because Japanese nouns usually do not mark singular vs. plural the way English does.

So 動画 could mean:

• a video
• videos
• video content in general

In this sentence, it most naturally feels like videos or video content in general, because the pattern 見てばかりいる suggests repeated or continuous behavior.

Not exactly.

Both can relate to the idea of only, but they feel different.

• だけ is more neutral: just / only
• ばかり often suggests too much, nothing but, or a mildly negative judgment

Compare the feeling:

• 動画だけ見ている = only watching videos
  
  • fairly neutral description
• 動画を見てばかりいる = doing nothing but watching videos
  
  • sounds more critical or annoyed

So in this sentence, ばかり is a better fit because the speaker is pointing out a bad habit or an unbalanced action.