Stock price when the opinion was issued
ZDI uses the MSCI World Universe International Developed Markets index, which does not include exposure to South Korea. VIDY uses the FTSE series, which does include South Korea. That's the main difference, along with a slight difference in MER (ZDI slightly more expensive).
Focus on the exposure, not the MER. You have to make a call whether there are enough good dividend-paying stocks in South Korea to want to choose VIDY. Remember, these dividends don't get preferential tax treatment, it's all income. So if you're looking for income in your taxable portfolio, you get a much better tax experience with capital gains from the covered call overlay.
The only issue he has with this is that these are all foreign dividends, so you are not getting the dividend tax credit. It is all coming in as straight income. Other than that, he has no problem with it.