It's a backwater that is far from anything he was interested in and had appeared only relatively recently.
the shire was ~1400 years old by the time of the books, so not that recently.
but it was far from sauron's borders, wasnt a great power, not even a kingdom. it was in the territory of what had been arnor, and he'd already smashed arnor a thousand years ago or more. sauron also didnt think much of the other factions of western middle earth, he basically thought that as long as he could defeat gondor and prevent the already failing elves from fucking around, he would win. there was no need for him to deal with random little settlements like the lossoth or the shire.
plus, it had the name "shire", which is as generic as you can possibly get (Sûza is the Westron word for "province, sphere of occupation, division of a realm",[1] visible in Sûza-t, "The Shire").
Without watching the video because I'm about to go to bed
I'll assume Sauron never heard of the shire for the same reason Darth Vader never heard of Dagobah (as far as I know, unless some supplement asspull changed that): it's just some place that's kind of there and not immediately relevant to the big bad guy's plans or goals.I found a YouTube link in your post. Here are links to the same video on alternative frontends that protect your privacy:
