The standard release of Firefox is a 32-bit program, so you can use the 32-bit version of Silverlight. If you visit the following page in Firefox, Microsoft should steer you to the proper download. Does this address work?

https://www.microsoft.com/getsilverlight/Get-Started/Install/Default.aspx

But... most video sites probably use Flash rather than Silverlight. For that download, see Adobe's site here:

https://get.adobe.com/flashplayer/

By default, some extras are included that you may not want, so make sure to review and uncheck those if you don't.

Sorry for not including this in the last message, but when the forum polled your plugins, Flash did not show up (Question Details > More System Details next to your post). If Adobe's installer says you already have the version for Firefox, please check the Add-ons page to see whether Flash is disabled. Either:

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

In the left column, click Plugins. Look for "Shockwave Flash" and if it's at the bottom set to "Never Activate" change to either "Always Activate" or "Ask to Activate".

With the "Ask to Activate" setting, also known as "Click to Play," when you visit a site that wants to use Flash, you should see a notification icon in the address bar and usually (but not always) one of the following: a link in a dark gray rectangle in the page or an infobar sliding down between the toolbar area and the page.

The plugin notification icon in the address bar typically looks like a small, dark gray Lego block. (If it's red, Flash needs updating.)

If you see a good reason to use Flash, and the site looks trustworthy, you can go ahead and click the notification icon in the address bar to allow Flash. You can trust the site for the time being or permanently.

But some pages use Flash only for tracking or playing ads, so if you don't see an immediate need for Flash, feel free to ignore the notification! It will just sit there in case you want to use it later.

Note in order to use Win64 Firefox you need 64-bit Windows 7, 8(8.1), 10 as 64-bit Windows XP and Vista can only run 32-bit Firefox.

You have 32-bit Firefox on 64-bit Windows Vista so you need 32-bit Plugins.