The technical advantages of monitors are valid reasons for higher cost (refresh rate, response time, color accuracy, gsync/freesync), but as mentioned in the video itself, TVs do have enough tech that monitors don't to offset those differences (size+resolution, brightness uniformity, OLED/curved/thinness options), so it should be a wash.

However, the video you linked doesn't really address the advertisement subsidy point at all (I searched the transcript for any references to make sure), so it isn't really an argument that the ad-subsidy is a myth. Plenty of reporting and discussion and evidence that traditional TV advertising industry (untargeted cable/broadcast ads) is declining in revenue, but the overall TV ad industry revenue is growing (share taken up by smart TV and streaming service ads) is going up. Streaming services absolutely use platform data where they can access it (ie smart TVs). A 1997 article sounds like it would have no context whatsoever about the 2020 smart TV advertising landscape (very very different from traditional TV advertising).

Ad revshare is just so lucrative, especially for ~$0 cost/unit for the manufacturer that it pays for every smart feature and onboard computer and then some. The difference in cost for net-comparable features is still apparent — the cheapest monitor at size-resolution combo X with worst refresh rate/response time/color accuracy is still more expensive than the cheapest smart TV at X (roughly comparable features).