I like to watch YouTube videos related to technology, gadgets, etc… I’ve noticed that none of the content creators I watch use ad-blockers when they screen share a webpage. I find this unusual because some of them have recommended using an ad-blocker for personal use in their videos. I also get the impression from what some of them say on camera that they actively use them when off camera. To make matters more confusing, sometimes they’ll share video clips from one website or another but they’ll omit the advertisements from those videos completely. What’s the deal here? Selective ethics? Really fine print?
It’s possible that they are doing the demo for video on a fresh VM that they set up for the purpose - to avoid accidentally sharing some small aspect of their identity in the video.
For example on an Amazon page, your name is in several places on the page, and your post code pops up here and there in delivery options etc. You can of course blur these out in the edit, but that’s effort, and it’s easy to miss one.
So the short answer might be: you’re not watching what they normally do.
Edit: I mean, also, I’m surprised that many of them do actually recommend ad blockers, given that ads are a revenue stream for them.
Ad blocking is a highly effective method for preventing malware infection, so it’s understandable that tech YouTubers would recommend it for that reason even though they likely also benefit monetarily from ads too. Still, bigger outfits like Linus Tech Tips or Snazzy Labs get a lot more of their revenue from onscreen ad reads/plugs (and now a word from our sponsor) than they do from YouTube pre-roll or popup ads. They also sell merch, have Patreons, and in a lot of cases they ask you to whitelist their ads (not so easy to do on YouTube than on a website, admittedly).
I think Mangetout is most likely right that whatever they’re demoing is usually something in a rather vanilla virtual machine or freshly cloned OS install. LTT even did a whole video about why so many of their demos show “Activate Windows” in the corner. They reconfigure hardware and software so often that activating just causes more headaches than leaving it alone. They’re erasing these systems and re-imaging them in days if not hours, so it’s best to just keep them as clean as possible. Plus, ad blockers can have a non-trivial impact on performance, and an ad-free web browsing experience may not be the most common real-world scenario that they’re trying to benchmark.