Hello, I noticed that some of the indie games make appearances on IGN.com, GameSpot.com and GameTrailers.com I could not find a link "Submit a video" or similar link on neither the portals. Do you know by any chance how to get my trailer and preview/review up there? Thank you.

You just send it to them. But they're not likely to do anything with it unless you've got a good story (like you won a competition with it, you've got a million viewers of your trailer on YouTube, the local newspaper did a story on you because your cat plays your game online and beats all comers...)

I am not sure about that. The game I saw on gametrailers is nothing special. Just another vertical shooter. It's IGN and GameSpot pages are empty (with two lines about the game). So, there should be another way :)

You issue a press release, which you send to the various sites telling them about your game and providing a link to the screen-shots and/or video that you host. You make sure to tell them the important facts about your game... format, price, release date, 5-10 key features etc.

Spend time checking which sites cover which formats, track down the right person and send them a personalised email with the press release. Some will cover the story, some wont.

Thanks Obscure.
Do you know where can I look up nice press release to learn who to write it and how to make it look attractive? Thanks.

Just Google Press Release Format or Press Release Layout.