The perception of offsides in front of the TV strongly depends on the camera perspective in the stadium. I often enough got into the trap to think "clear offside", when corrected camera angles proofed me wrong. Offside Explained has numerous examples of such situations, which become even more complicated when the TV station does not stop the picture at the moment of the pass or header. The human eye is subject to some perceptual errors like the so-called flash-lag-effect shown by Baldo, Ranvaud and Morya (2002) and discussed by Helsen, Gillis and Weston (2006) - for a quick description and practical examples see a collection of Offside Explained.
As said: We as spectators have to hope that the TV directors stop the moving pictures at the right moment. Assitant Referees don't have this deluxe as we all know. But back to our concrete example: Was it offside at all?
As indicated, yes, it was. But a very small offside position. I have adjusted the camera angles (see above) using Adobe Photoshop, calculating distances between the grass lines in the turf and the players (attacker and 2nd last defender). These two players' different distances to the next drawn line (the one going through the penalty mark, i.e. the left black-coloured line) differ by approximately 4,5%. Mutiplying this with the usual 5,5m width of a drawn turf line, the result is 24,75cm. These 24,75cm are the distance between the 2nd last defender's most forward part of the body with which you can score a goal and the attacker's most forward part of the body with which you can score a goal. If the attacker had been 24,75cm more to the right, he would have been perfectly level with the 2nd last defender. So we cannot say that this was an offside by 24,75 cm...but rather by maybe 10-20 cms.
Serbian assistant referee Dalibor Đurđević did what is recommended in such situations. If there are doubts about an off- or onside position, the benefit of the doubt goes to the attacker. Same applies for referee observers. In such high-pace passes, where an accurate decision is tremendously difficult to process for the human eye, the assistant referee cannot be reproached for some centimetres. He has to be supported. In dubio pro ref, as I tend to say in these cases. And: The 2nd onside a second later was all right as well.
So: This situation is a good example of an armchair offside. Of course, this does hardly matter as the overall image most spectators have received - fueled by distorted camera angles - is that it was an offside... nobody cares how much offside it was.