Compared to what though? I know pretty much zero about shooting video, but the few times I've shot a short clip with a DSLR (handheld) I did find IS helped cancel out a bit of wobble. An external mic is usually required to not pick up the IS noise in the recording though.
If you're meaning that IS is a joke compared to some sort of proper stabilising rig (or video tripod) then sure - "proper" kit will always be way better.
It's a joke for any long take. If you splice and dice in post process, then sure, it's fine, but so is a monopod at that point. If you're talking about your kids, sure it'll work in a 10 second pinch. But it's a joke in any professional capacity. And hence, saying that the Tamron is "better for video" is just blatantly meh and telling of that poster's lack of video experience.