It's an artefact of the video compression. The chair was sitting in front of the table and the guy just picked it up and threw it out of the way.
And it's strange. Because, as I've read and several people have pointed out, how is it possible that with the quality of today's cameras you can get such a poor image? Yes, the simplest and most sufficient explanation is the most likely, but not necessarily the true one, considering the other inconsistencies that are being reported. I admit that when I see this, I find it difficult to think in purely materialistic terms...