I found a video of Ore no Imouto's 9th Ending Suki Nandamon and it says "Original Edition". It is different from the TV version sang by Ayana Taketatsu, the actual version of the ending of Oreimo. But the singer sounds a bit different from Ayana Taketatsu. I don't know if the Original Version and the TV Version have the same artist. So I'm asking, is Ayana Taketatsu the artist of the Original Edition? If not, who is the artist?
As far as I know, the TV broadcast and the DVD have the same version of "Suki nan da mon", sung by Ayana Taketatsu.
The video you linked is a cover of the song by an amateur artist named Misaki Arima. Her name is printed in the info under the video, as well as on the background pic in the video itself; the line 歌：有馬美咲 means "Singer: Arima Misaki". As senshin pointed out, the line 「歌：有馬美咲 ★本編は竹達彩菜さん★」 in the details says "this is sung by Arima Misaki, but the original is by ★Taketatsu Ayana★". Arima's Facebook page (which was all I turned up in a Google search of her name) lists Ore Imo as a favorite novel and has the same profile picture as her Youtube profile, which you can see on the video page.
The video itself just claims to be the "Full version", which it is (not the edited TV version of the song). I'm not sure where that commenter got the idea that this was the original version, but, well, you know how commenters can be...
(Actually, I think the commenter probably meant "original-length version".)