We are using a lot of vimeo videos where we as a security measure restrict access on a domain, such that videos can only be embedde on eg. acme.com 

Vimeo has recently updated their embed code for restricted videos so that the syntax has gone from: 

<iframe src="https://player.vimeo.com/video/YYYYYYY/XXXXXXX" ></iframe>

<iframe src="https://player.vimeo.com/video/YYYYYYY?h=XXXXXXX" ></iframe>

The moodle multimedia filter will automatically try and create an embed link if a vimeo link is inserted and the links given by Vimeo are still in the format: 

https://vimeo.com/XXXXX/YYYYY

This causes moodle to generate an embed url on the old format which not cause Vimeo to display a "Sorry This video does not exist". 

We have been in contact with vimeo support about this and the confirm the change: 

Thanks for reaching out to support at Vimeo.
 
For additional security, we’ve introduced a new privacy hash into the embed code of videos going forward. The player link will not function without the additional code, which is present in your full embed code, but easy to overlook.
 
When copying and pasting your embed code, be sure to include the string of letters and numbers after the ‘h=‘ parameter in the embed code. 
 
As an example, they’ll look like this:
 
h=5c4dedfc34
 
​​
 
Not including the privacy hash will lead to the video not being available for viewing wherever it's embedded.
 
Links to private videos themselves, on the other hand, will have the hash at the end of URL, without the 'h=' parameter.
 
So as an example, if a video has a privacy hash of 'h=9ea73a6a07', then the link of the videos will look like this: [*https://vimeo.com/123456789/*] 9ea73a6a07