Hello JerseyStARFoX737, I suggest you place a printscreen of what you are seeing when the error occurs. I know that this is annoying to ask something like this, but it could help us understand what is happening. Thank you

If you use extensions (Firefox/Tools > Add-ons > Extensions) that can block content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then make sure that such extensions aren't blocking content.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Clear the cache and only cookies from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > Cookies: "Show Cookies"

If you click the link in my original post, you'll see I have included a screen capture of my exact issue. :)

Okay, so I did what you said about restarting Firefox in Safe Mode to see if that did the trick, and it does. Embedded videos once again show up, so it must be one of my Add-Ons. However, is there a way to pinpoint exactly which Add-On is causing the trouble? It would be nice if I could instantly pinpoint this without having to manually disable each and every Add-On individually while leaving the other ones on, considering I have quite a few. I do have Ad-Block out of the possible Add-Ons you mentioned, but I've always had it and it never gave me trouble with embedded videos being displayed on the page. If need be I'll resort to the manually disabling each one at a time to test them, but most of the add-ons are for displaying Firefox in a way that resembles the old versions compared to the newer version. And again, they never gave me a problem. But it would be nice if there's a way I can instantly pinpoint which one is giving me the trouble.

You can check which content is blocked by ABP on the YouTube pages and disable involved rules to see if that helps.
We've seen more post lately that ABP is blocking content, so that is the most likely candidate.

You were right, it was APB. I selected "Disable on this page only" and refreshed the page, and the embedded video showed up again. Thanks for the help!

...On another note, I wonder if it will ever go back to being able to have ABP back on again without worrying if embedded videos show up or not.

Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the Clear now button.

Further information can be found in the Clear your cache, history and other personal information in Firefox article.

Please report back soon.

I cleared my cookies and cache, and while it seems doing this fixed another previously unmentioned issue I had with YouTube comments not displaying unless I was logged into my account on that site, it didn't quite solve my problem of ABP blocking embedded videos from showing up, without having to manually disable it every time I want to watch em embedded YouTube video on any given webpage.

Try disabling graphics hardware acceleration. Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

Then perform these steps:

• Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
• In the Firefox options window click the Advanced tab, then select "General".
• In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
• Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Did this fix your problems? Please report back soon.

You're welcome.

Maybe ask advice at the ABP forum.

• https://adblockplus.org/forum/