Is that a "Clear and obvious error?" Need a linos call for such a marginal decision like that, like cricket reviews with umpires call for lbw
Yes, it is. The video shows he is, by the current definition of the law, offside. You cannot score a goal if you are offside. To allow a goal to stand when you know a player is offside is a clear and obvious error.
The offside itself is marginal, but that's not where 'clear and obvious' is applied. And there is no provision in the current law for gradations of offside. You are on or off. He was off, ergo he cannot legally score.