It appears to load properly for me. I get the page with an embedded Vimeo window that says This event hasn't started yet.

I do see that there's a <video> element on the page that produces a 410 error code because the file it's linked to no longer exists, but that happens in any browser that I've tested it with.

Perhaps I'm not fully understanding the issue that you are having, but all looks good to me.

Hi Wesley - thanks for the reply first and foremost, and for taking the time to look.

To explain the 410 error - I found yesterday that the Vimeo link to the file actually resolves to something else, so I changed the video src to that and it worked, but I've realised since your post that this is obviously a time-limited/hash-verified URL and thus doing that is not a solution.

For example., the original permalink to the file from Vimeo: https://player.vimeo.com/external/383320811.sd.mp4?s=eb41f8a9ba375790bb9e3d9e1238fa6e931ef9a8&profile_id=165 resolves to: https://vod-progressive.akamaized.net/exp=1578841109~acl=%2A%2F1610040407.mp4%2A~hmac=1b46f12a85dff0e69e9b5a28deb854ba21cf375211b5378ce4c58456688aa10f/vimeo-prod-skyfire-std-us/01/1664/15/383320811/1610040407.mp4 - but this might just be for today

Both of these will load directly in the browser.

But you should see that when used as a background video on https://dancersvscancer.co.uk/ it does not load, failing with a 403 unless you are in a private window:

HTTP load failed with status 403. Load of media resource https://player.vimeo.com/external/383320811.sd.mp4?s=eb41f8a9ba375790bb9e3d9e1238fa6e931ef9a8&profile_id=165 failed.

I have tried both in regular mode and private mode and the video won't play in either for me. That's because it's blocked by Enhanced Tracking Protection (ETP) as a Cross-Site Tracking Cookie.

When I reloaded with ETP disabled, it loaded properly.

Thanks again.

I used exactly the same technique on this site: https://smarts.agency/ - yet these videos play perfectly in both regular and private windows on Firefox.

So I'm pretty confused as to why the other one won't play. And I can definitely get it to work on a private window - not sure why that isn't working for you.

Even more bizarre - I have not made any configuration changes to either the website or Vimeo but the background video appears to be working for me now. Very odd.

I see Ghostery in your System Details list.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows an highlighted shield icon at the left end of the location/address bar in case Tracking Protection is blocking content.

• click the shield icon for more details and possibly disable the protection

You can check the Web Console what content is blocked.

• "3-bar" menu button or Tools -> Web Developer
• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop

Thanks cor-el

I have checked my settings and everything is default - no content is being blocked.

As I mentioned before, it is very confusing as with no change to either the website or Vimeo, the background video is now playing perfectly.

Thanks to you and Wesley for taking the time to help.

Yeah, that's an odd one. I can also play the website fine with ETP enabled. Must have been an issue on Vimeo's end.

Glad it's working now!

It was short-lived. It's not working again. Very strange issue.

I don't believe it's at the Vimeo end since it works on all other browsers.

I must admit I'm completely foxed by this.

It works when I click the icon to allow auto play.

• https://support.mozilla.org/en-US/kb/block-autoplay

Thanks - I don't think that is the issue.

As Wesley confirmed, the background video was working fine yesterday with no changes to Firefox settings.

I built this website - it uses an identical approach to the video: https://smarts.agency/ - yet these videos play without a problem, without changing any settings.

This is why I'm finding this so confusing - it's very inconsistent and I cannot see a reason for it. Also the background video plays fine for me on https://dancersvscancer.co.uk/ if launched in a private window.

Did you check the Web Console for medai related messages ?

Yes, I posted them in a previous post:

HTTP load failed with status 403. Load of media resource https://player.vimeo.com/external/383320811.sd.mp4?s=eb41f8a9ba375790bb9e3d9e1238fa6e931ef9a8&profile_id=165 failed.

Video loads fine if accessed directly.

Are you possibly using containers or container related extensions ?

• https://support.mozilla.org/en-US/kb/containers

I have absolutely no changes to the defaults of Firefox as it is shipped.

Here are the facts to summarise once more:

1. The background video loads if launched directly: https://player.vimeo.com/external/383320811.sd.mp4?s=eb41f8a9ba375790bb9e3d9e1238fa6e931ef9a8&profile_id=165
2. It loads on Firefox mobile
3. It works in a private Firefox window
4. It works intermittently (all day yesterday, for example, there was not an issue)
5. It works on other browsers
6. An identical background video embed technique using the same Vimeo account with identical privacy and embed settings works fine on https://smarts.agency (I built that site too)

Error is: HTTP load failed with status 403. Load of media resource https://player.vimeo.com/external/383320811.sd.mp4?s=eb41f8a9ba375790bb9e3d9e1238fa6e931ef9a8&profile_id=165 failed.

Did you try to clear the Vimeo cookies?

You can remove all data stored in Firefox for a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data for that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Hi cor-el - thanks for continuing to help with this issue.

I tried that, but to no avail. I ran the "Forget about this site" and restarted Firefox, but the problem persists. The only way I can get the video to load as normal is to use a private window.