For example:

Check the 11th link for "Play Video" on  https://www.manhattanprep.com/gmat/thursdays-with-ron/

There is no icon to download. Though, it exists for first 10 links. Below is the snapshot for 10th and 11th links for reference.

Browser: Opera-Webkit 520 Windows
User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36 OPR/52.0.2871.99
Extension: opera-chromium 7.57

I am trying to download via extension. Open the below website and hover over the links mentioned "Play Video". You can see there is download icon for ones which vimeo.com/** but not for https://vimeo.com/***..Youtube links are working fine BTW.

https://www.manhattanprep.com/gmat/thursdays-with-ron/