How should we handle edits that add info to an answer beyond what the OP intended?

Question

What's the policy when a new person edits a post to add significant info to an answer that wasn't there in the first place. The info isn't wrong per se, it's just a notable chunk that's new.

In particular this edit was in the queue this morning. (Here is the original 8-year-old answer link in case the edit review queue is cleared and that won't come up again.)

Here is the added text:

However, manufacturers may recommend that the high pressure line carrying condensed refrigerant should be insulated if that line runs through an attic and the attic temperatures exceed 120 degrees. That is because the liquid line (which, in a properly charged system, should be about 4 degrees above outdoor temperature when it leaves the condensor) will pick up heat as it travels through the hot attic. So all that work the condensor did to remove the heat is now being added back by running the uninsulated liquid line through a blazingly hot attic. You should consult your condensor's service manual for the manufacturer's recommendation on this. I insulated my liquid line, and now, on hot summer days, my AC runs less often, and my indoor humidity has dropped by 4 percentage points because the liquid coolant reaching the evaporator is ... well ... cooler!

For additional explanation, see https://youtu.be/QDIKtN3J3S0

It includes a YouTube link which I have not clicked, so I don't know if this is spammy, appropriate, etc. or not.

Realistically, I'd think that the editor should be directed to make his own answer indicating that this is "supplemental info" to the "other very good answers", or perhaps linking to the specific answer he targeted.

Again, it's not wrong info, it's just above and beyond. My understanding that edits are supposed to improve a specific answer in terms of spelling, grammar, formatting, etc., not adding more info.

Answer 1

This is a good question, and to me it comes down to individual ownership of answers or the opportunity to approve of content attributed to the individual. I tend to think of SE sites as wikis, with open contribution from others welcome, but when my name is on it I'd rather not have large blocks of content added that I haven't approved and may not agree with or consider relevant to my answer.

Since no canonical answers have come along I'd maybe suggest that it be left up to the answer author. I seem to recall being notified of such edits, probably when made by newer users, but I'm not sure whether that always happens.

So maybe, if we notice that such an edit has occurred, and authors aren't always notified, we simply comment on the answer to alert the author. I would, though, revert any edits which I don't consider to be very well aligned with the original intent of the answer.