After the 3.1.0.beta4 update, Vimeo oneboxes were broken, displaying as lazy-video-wrappers instead of iframes, and thumbnails were missing for unlisted videos Nacho_Caballero. This was due to a change in how embeds are handled, with Vimeo embeds now lazily loaded jancernik. The issue affected topic thumbnails, but could be resolved by disabling the lazy_vimeo_enabled setting jancernik. A workaround using Open Graph images was proposed Richie, and a fix was implemented in Discourse PR #21343 to source thumbnails from Open Graph, resolving the issue jancernik. Richie praised the fix for improving consistency.
It appears the vimeo onebox is now shown as a lazy-video-wrapper instead of an iframe.
A vimeo URL now appears like this:
Image version:
Instead of showing the thumbnail, like it used to. Image version:
This doesn’t affect old urls (only new/rebuilt). See old vimeo onebox.
The lazy-video-wrapper that you see is a part of a change we made three weeks ago in the way we handle embeds. Vimeo embeds are now lazily loaded, which means that the iframe is only appended on demand.
https://github.com/discourse/discourse/pull/20722
Missing thumbnails are a known limitation with unlisted Vimeo uploads. There may be a workaround, but we are still investigating it. For more information, please refer to
Thanks, Jan.
For now, I can manage by inserting iframes instead of raw URLs:
Something else that might be worth considering is that the image associated with the lazy wrapper is picked up by the Topic Thumbnails plugin and this also breaks my topic thumbnails. I don’t know if there’s a way to ignore it.
If you really need thumbnails, you can disable this feature with the lazy_vimeo_enabled setting, instead of inserting the iframes yourself.
Good to know. It might be hard to discern, but we’ll see if we can do something about it.
That solves my problem entirely. 
Am I just giving up on a bit of performance or is there an additional benefit to lazy loading?
The main reason of lazy loading performance, yes. You also get additional benefits such as better search engine optimization (SEO) and improved accessibility, but you should be fine leaving that disabled for now.
Could you use the opengraph image as a thumbnail? 
For example, this URL: https://vimeo.com/795669787/0763fdb816
Returns a og:image value of: https://i.vimeocdn.com/video/1602645154-56e0101b545c38ae03e9bc65ae12c3bcc37cd8ea127d359c0d24cf8ab31f8675-d
Which (correctly) displays as:
Yes, that was exactly my idea. In theory, it should work, but I haven’t gotten to test an implementation for it yet
After this change, thumbnails are now sourced from Open Graph instead of the oembed. All Vimeo videos should have a thumbnail now:
This is an excellent fix and provides great consistency.
Thanks @jancernik 
