This is a tool which is very useful especially when expanding on your campaign, if you had a campaign or adgroup which had your location specified e.g. “London”, you could duplicate this campaign or adgroup and replace it with “east London”, “west London” and many other locations which may be relevant to your campaign.
In the video above I replace google with bing, so one minute I have a campaign about Google Ads management and then just by using this tool, one minute later I also have a bing management campaign instead of having to create one from scratch which may take hours.
This tool is not limited to expansion though, any time you have keywords in your campaign which you want to get rid of and replace with something else, this will do the trick. Just be sure you are implementing the correct changes though (using the preview tool), as when making bulk changes, if you do it wrong once, it may be an error repeated thousands of times!