I thought "everyone" already agreed on this. Video files are smaller and if you choose the right set of codecs for which clients have hardware acceleration then playback consumes less energy, meaning your visitors don't drain the batteries of their devices as fast.
> replacing GIFs with video has now been common for a few years
Indeed. Which kind of leaves me wondering why author seems to be introducing their article as though it wasn't.
Of course, the article does go on to argue for a specific codec. Still, to me it seems to talk in a way as if not using GIF is "controversial".