Hello Linh!

Punctuation:

It goes without saying that television is just like a wonder box, which contains many kinds of information.

No comma is needed. The phrase “which contains many kinds of information” is a necessary or defining or restrictive relative clause, so you should not use a comma. Try the quiz at http://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?04 and the information at the end of the page at http://www.gcu.ac.uk/student/english/selfstudy/grammar/relativeclauses.html or at http://www.myenglishpages.com/site_php_files/grammar-lesson-relative-clauses.php

Introduction:

Although it plays a positive role in the cultural development, its detriments may be colossal as well.

You have given two sides. However, it would be stronger if you gave some examples of television’s positive and negative effects on culture. You could give write:

Although television can develop culture by showing classical dance and drama, it can also numb young minds with endless formulaic American sitcoms and mindless chat shows.

The word ‘colossal’ is too strong. It’s a good word, but it’s for earthquakes over 8.0, asteroid crashes, and Zimbabwe-style currency devaluations. Not every IELTS topic is “contentious”, “earthshaking” or a matter of “urgent debate.” Some are very boring. Really.

Clichés: tired old phrases

“It goes without saying” is a tired old phrase or cliché which really means that the writer could not think of something to say. Just leave it out. Use it in speaking only, where redundancy and repetition are more important.

Other tired phrases are:

• “both sides of a coin”
• “a double-edged sword”
• "It is high time that…"
• “no body can deny that..” (Yes, we almost certainly can)

Conclusion

I would love your opinion. Task 2 in IELTS is an opinion essay, so give it. Be careful with sentences like:

As shown above, [the] positive effects of the tube seem to outstrip [the] negative impacts on the cultural development.

Why?

First of all, “as shown above” makes the reader go backwards. Good writing goes forward. You might need to tell the reader to go back if you have written 2500 words, but here it’s only 250, so the reader should probably still have a good grasp of your ideas…

Secondly, the reader wants to know WHY the positive effects outstrip or outweigh the negative impacts.  If you give three positive and three negative examples, why is one set stronger?

So you might write

I believe that television, despite its mindless sitcoms, endless chatter, and over-reaction to current events, can be a powerful force for the spread and development of national identity because of its X, Y and Z.

Good examples

One strong part of your essay is your examples. These sentences tend to be concrete, clear and error-free.

Compare these three clear sentences:

• In Hue or Tay Nguyen’s songs, people enjoy a chance of immersing themselves in cultural essences, which reminds them of their roots and facilitates their national pride.
• In today’s world, almost all youngsters wear Levis’ jeans, listen to music by Ipod, and eat KFC regardless [of] their nationality and religion.
• To taste and maximize profit, action Hollywood films [and]  romantic Korean films are more and more predominant in TV shows, putting traditional artistic types like reformed theater [and] classical drama at the risk

With this not-so-good one:

• Moreover, adoring customs of dissonant cultures all around the world not only enlighten their mind, but stimulates innovativeness in creative fields like fashion, art also.

In the first three sentences, there are almost zero errors and the meaning is immediately understandable. In the last sentence, however, there are vocabulary errors (“adoring”, "innovativeness"), agreement errors ("enlighten", “mind”), missing articles, unclear pronoun references, and missing conjunctions. It's flowery, as well, which can be a little dangerous.

Keep your idea sentences simple and short, and give more of your excellent examples.

Moreover…

Just a reminder  from my comments on some of your other essays: there's no need to start every sentence with an introductory phrase or marker or cohesive device, as IELTS calls them. It makes your sentences bitty. Just say what you want to say.

For example, in Paragraph 2, the sentences start with

• To begin with
• That is to say,
• People, hence, are
• Moreover,
• This, in its turn,

Use them sparingly: One or two per paragraph, at most. Check what it says in the IELTS Writing Task 2 Public Descriptors (the first link on this page http://writefix.com/?page_id=1774about cohesive devices and their overuse under the heading Coherence and  – you definitely don't want to be a Band 5!

Sorry if the feedback is a little overwhelming!

Thanks Linh!  Glad links are working now. Thanks to Flor for helping me with the error message.

I will try to get around to working on your globalization essay sometime soon. Or would you like to revise it first?

Of course, everyone else is welcome to comment on it as well!