1) the first youtube video does indeed instruct how to replace the upper/lower scan boards, but this is on an older set from 2007, so its not quite relevant in this case.
2) the second youtube video shows an issue (vertical line, again, not relevant in this case) that disappears after the person changes the input source indicating that its more than likely not a tv issue (pressing the menu button on the samsung remote with that line on the screen would have clearly indicated if that was a tv issue or not)
3) how did you manage to get a bigger picture if you are not the OP ?