From Torontoist back in December:
“The strange plaques were part of the grand Gestures installation by the 640 480 Video Collective, which aimed to memorialize inconsequential events captured on video at ten spots around the city. Each marker was placed in September and describes the unexciting details of a YouTube-sourced video shot at that particular location (like the ones above at left and at right)....
640 480 takes its name from the original 4:3 aspect ratio of video screens, and the group has an obvious affinity for the rapidly disappearing magnetic tape format. Memorial lapel ribbons made from videotape were also part of the grand Gestures installation, and taped copies of the videos are to be converted into an artificial diamond, signifying the preservation of memories from an increasingly obsolete format into an everlasting state.”
More info here.