If you right-click the player area, which kind of player does it seem to be:

• built-in HTML5 player: long Firefox context menu with video-related commands at the top
• plugin player: short context menu that usually mentions the relevant plugin's name toward the bottom
• no player: regular Firefox context menu

If you get no player:

Could you check whether Firefox is waiting for you to approve a plugin to run on the site:

The plugin notification icon in the address bar typically looks like a small, dark gray Lego block. (When the page wants to use a blocked plugin, the icon turns red to alert you to the concern.)

You can click the notification icon in the address bar to view the requested plugin and allow or block it. For allow, you can trust the site for the time being or permanently.

One comment about your plugin list (next to your question, Question Details section, More System Details):

Your Adobe Acrobat (PDF) plugin is out of date. This could indicate that your Adobe Reader/Acrobat software is out of date, since the Adobe Reader/Acrobat software also updates the plugin used by Firefox.

To address that, please open Adobe Reader/Acrobat (the program itself, not in Firefox) and use the Help menu > Check for Updates.

The latest release of the Acrobat/Reader 11 (XI) series is 11.0.16.

If you have uninstalled Adobe Reader/Acrobat, I recommend disabling the Adobe Acrobat plugin since the older versions have known security problems. You can do that on the Add-ons page, either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, look for "Adobe Acrobat" and change its permission to "Never Activate".

You can set Firefox to use a different viewer on the Options page. See: View PDF files in Firefox or choose another viewer.

Adobe acrobat says that it is the most current version, so that is not the problem.

It is a vimeo video player and has only been problematic since I "upgraded" to firefox 47

Can you give me feedback on my question about the embedded player on the page?

And later we can figure out why Firefox is reporting an out-of-date Acrobat plugin, unrelated to your video issue.

I answered your question about the type of player in the last response. It is a vimeo video player. When you "right click" the player you get a menu of a bunch of options of what to do with the frame that the player is in.

Some change in firefox 47 is the problem as there are other people reporting the same problem since they "upgraded", and I was able to play embedded vimeo videos without problem prior to the latest and greatest.

Okay, that sounds like a "native" HTML5 player.

Maybe it's an XP thing because I don't see a problem on Windows 7... but you may be viewing a different video than I was. Can you link to a page that has this problem?

This was the most active recent Firefox thread I found on the Vimeo forum:

• No Playback using FireFox on XP machine

There's no solution there, just a request to contact Vimeo for detailed troubleshooting.

here is the page: https://vimeo.com/107197071.

Is it possible to go back to the version of firefox that I had before that worked fine with my xp machine??

In case this was a change on the Vimeo site, could you test Firefox 46.0.1 using the "Portable" version? This is a stand-alone program you download and install into a folder, which does not interfere with your existing Firefox installation.

https://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./Mozilla%20Firefox%2C%20Portable%20Edition%2046.0.1/

Look for the FirefoxPortable_46.0.1_English.paf.exe file (you may need to adjust the zoom level on the page to make sure you get the right language version).