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.


it wouldn't cause me to sell mine and buy a IS version.

