If I want to take off a feed wire from mac (I have charged battery), then two last times it's very hard to get it out there. It's like clued or something like that. I need to exert strength to get the wire out from the outlet. What has happened?

It sounds like maybe the plug has gotten bent or deformed and is getting caught when you try to disconnect it. Try it in a different outlet -- if you have the same problem there, then replace the cable.

In my mac, I only have one outlet for feed wire. It's on the left side. Does your mac have severe of them?

"Outlet" means the wall outlet -- I gather that you actually meant that you're having trouble disconnecting from the computer. In that case it could be a deformity of the cable connector or the computer port may be damaged. It sounds like your options are to try a replacement cable (and/or try the cable with a different computer), and if the problem persists with a different cable then bring the computer to a service center.

If I don't change a cable for new one or don't go to service, will that problem effect badly to my mac? Or is it a local, a port problem?

There's no way to determine anything about the physical condition of your computer's connections remotely -- if it causes you operational problems then it would seem like you'd need to have it looked at at a service center..

What it means "operational problems" ? I watch a video Love runs out by OneRepublic (Vevo), since 1.02 is too dark. Is that an operational problem, or just too darkly recorded? Can you watch please in your computer the same video and tell me is it dark, too? Other video I watch in youtube is OK by brightness.. And some more are not.

"Operational problems" meant if the problem you're having with your cable connection makes it overly difficult or impossible to do work on your computer. I can't tell from here if your computer's display is not working properly -- if you think it isn't you should have it looked at at a service center..

OK. If I already will have operational problems, is it a fatal damage of mac, or temporary problem - fixing the cable and problems are gone.. ?

Again, there's no way a computer's physical/operational issues can be diagnosed remotely -- if you're having physical issues with the computer/connections then you should have it looked at at a service center..