Separate Issue; Your System Details shows;

Installed Plug-ins

Shockwave Flash 22.0 r0 Shockwave Flash 21.0 r0
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Flash: Grab the uninstaller from here: Uninstall Flash Player | Windows Uninstall Flash Player | Mac

Then reinstall the latest version.

Note: Windows users should download the active_x for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the active_x.

Flash Player Version: 22.0.0.192 Flash Player (Linux) Version 11.2.202.626

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download.

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download.

Separate Security Issue: Update your Adobe Reader Version 2015.016.20039 Note: Other Software is offered in the download.

http://kb.mozillazine.org/Images_or_animations_do_not_load

i tried following your instructions but it did not help. one piece of useful information is that i noticed on other streaming websites, when i place the cursor to a later part of the video, the preview image will show up, even on firefox. it is just on youtube on firefox that it does not show up

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

Type about:preferences<Enter> in the address bar.

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} A small dialog should appear. Click Start In Safe Mode (not Refresh). While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe websites. Are there any problems?

Then restart.

i tried clearing the cache and removing the youtube cookies. neither worked. again, it works on other browsers for youtube, and other websites even in firefox.

Did you try Safe Mode?

yes that didnt work. but i just noticed something very interesting: the cursor preview will work for youtube videos even in firefox if the video is embedded on another website! its just on the youtube website that it isnt working! what can i do??

Please post some of the bad links to check out.

its every youtube video which is the "bad link" which doesnt show the preview

Remove History For One Site Open the History Manager <Control><Shift> H. In the search bar, enter the name of the site. Right click on one of the listings and select Forget About This Site. This should remove all information, including any passwords / settings.

are you suggesting that i need to clear up memory for that site?

No. "Forget" cleans out all data about that site.

whats included in the data that will be lost?

Everything.