Hi CiaranLmore, I understand that Youtube videos have given a blank screen. Please try the following troubleshooting:

• Upgrade your graphics drivers to use hardware acceleration and WebGL
• Diagnose Firefox issues using Troubleshoot Mode to make sure its not an add on interfering.

Safe Mode also disables add ons and hardware acceleration, which may eliminate some of the root causes for the black screen. Also see: Fix video and audio problems on Firefox for Windows N editions

I am also seeing this issue.. With my laptop/desktop and users of a site I admin for.

I experience issues when using windows 7 x86_64, palemoon's current relase will work fine, but switching to FF37 the video plays for a few minutes then the audio stops working. I've also seen it where neither work and it just sits there, no errors in the console, no errors reported on the download server.

Other users have seen a variety of issues, documented here: https://www.animeftw.tv/forums/bug-reports/topic-4567/

Looking through the support board, this one appears to be related to the upgrade to 37 as well.. https://support.mozilla.org/en-US/questions/1058662

I am also experiencing this problem. Below is the error message received from the 37.0.2 Linux 64 mozilla tarball. The Fedora 21 version of firefox 37.0.1 does not have any problems. Windows 7 x86_64 is very problematic. It is fully updated with the latest drivers etc. Video will either stop or get corrupted as the sound continues to play. Does not mater what hardware is used. I have both nvidia and amd video cards in my machines as well as different sound devices with the same result. Error Code: A coding exception was thrown in a Promise resolution callback. See https://developer.mozilla.org/Mozilla/JavaScript_code_modules/Promise.jsm/Promise

Full message: TypeError: IO is null Full stack: exports.FilterStorage.saveToDisk/checkBackupRequired</<@resource://gre/modules/addons/XPIProvider.jsm -> jar:file:///home/usr/.mozilla/firefox/i2e3lynq.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/bootstrap.js -> jar:file:///home/usr/.mozilla/firefox/i2e3lynq.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/lib/filterStorage.js:598:13 onSuccess@resource://gre/modules/addons/XPIProvider.jsm -> jar:file:///home/usr/.mozilla/firefox/i2e3lynq.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/bootstrap.js -> jar:file:///home/usr/.mozilla/firefox/i2e3lynq.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/lib/io.js:306:1 Handler.prototype.process@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:870:23 this.PromiseWalker.walkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:749:7 this.PromiseWalker.scheduleWalkerLoop/<@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:691:37

1429727494499 Sync.BrowserIDManager ERROR Failed to fetch a token for authentication: [Exception... "App. Quitting" nsresult: "0x80004004 (NS_ERROR_ABORT)" location: "JS frame :: resource://services-common/async.js :: checkAppReady/onQuitApplication/Async.checkAppReady :: line 126" data: no] Stack trace: checkAppReady/onQuitApplication/Async.checkAppReady()@resource://services-common/async.js:126 < waitForSyncCallback()@resource://services-common/async.js:101 < makeSpinningCallback/callback.wait()@resource://services-common/async.js:145 < this.BrowserIDManager.prototype._getAuthenticationHeader()@resource://gre/modules/services-sync/browserid_identity.js:657 < Res__createRequest()@resource://services-sync/resource.js:168 < _doRequest()@resource://services-sync/resource.js:193 < Res__request()@resource://services-sync/resource.js:397 < Res_get()@resource://services-sync/resource.js:422 < Sync11Service.prototype._fetchInfo()@resource://gre/modules/services-sync/service.js:540 < sync()@resource://services-sync/stages/enginesync.js:77 < onNotify()@resource://gre/modules/services-sync/service.js:1278 < WrappedNotify()@resource://services-sync/util.js:148 < WrappedLock()@resource://services-sync/util.js:103 < _lockedSync()@resource://gre/modules/services-sync/service.js:1268 < sync/<()@resource://gre/modules/services-sync/service.js:1260 < WrappedCatch()@resource://services-sync/util.js:77 < sync()@resource://gre/modules/services-sync/service.js:1248 < <file:unknown>