In the video, he explains that he is not running wine or any other windows components of any kind. Yet, upon installing Imagination, he found in two of its temporary files, two windows based trojans. After looking up this DVD software program "Imagination" and going to Source forge to check it out, Ublock, stopped me from accessing the page..
Now this is probably where terminology comes into play, and how ones perspective of it may differ..
With humans, one can carry a disease without actually being sick, and is still considered "infected".. I would assume this applies to computers as well, if they were to carry a piece of malware, without it being active on that particular system, it could still be considered "Infected"
A question up above, and a very good one, is why did the two pieces of windows based malware sitting in temp files for the program, stop it from opening and being used on linux..
Bottom line, is that there are many that claim, linux never gets infected, you never need to scan it, or worry, and that is just plain wrong, and the point that he was trying to present in the video.