Some Vimeo / Streamable videos have a privacy protection to prevent them from being played outside of Patreon, so to fix this issue you have to:
For PC
Install the Referer Control extension on you browser (Available for Chrome & Firefox)
Click on it to open the options, and enter the link https://player.vimeo.com/video/ there, and click on custom and then finally type https://patreon.com/ below (Make sure you did it like in the below image)
Now you’ll have to change the main reaction video link you wanna watch from this format (4th & 5th Step ) — (if it’s not already)
For Vimeo Videos From https://vimeo.com/12345 to https://player.vimeo.com/video/12345 [ adding /video/ after .com ]
For Streamable Videos From https://streamable.com/abc to https://streamable.com/e/abc [ adding /e/ after .com ]