What he is talking about is that back when gifs and videos were both postage stamps pushed over modems, gifs won out.
But what changed was that people simply started ripping frames from HD videos, dumping them into gifs and plastering them all over social media.
End result was that the gifs ballooned in size because they now held many more images, and each images was much higher resolution.
What is more wacky is why gifs returned to fashion at all. They were dead for nearly a decade after people stopped doing their own web sites, and used gifs for things like animated "under construction" signs.