Youtube Videos not working as prescribed.
 

I installed flash-plugin to my knowledge and have Mozilla firefox, that is the version provided in my original slackware install and when I play certain youtube videos, sometimes randomly and sometimes for certain videos only I get static and an error message stating: "Your browser does not recognize ANY of the video formats" currently known to the human species, offering me the option to learn more about the awesome power of HTML. What is going on?

What is going on is that you should stop using Flash along with most others and use HTML5.

Flash had its day, but so did the Model-T.

I don't even know if YouTube offers flash videos anymore. It might all be HTML5 now.

I believe HTML5 video on Firefox with Slackware has additional requirements, but I can't remember for sure what they are. It might be ffmpeg, or gst-libav? Hopefully someone in here using Firefox can chime in. If you want YouTube to just work and don't care what browser is used, Chrome is able to play it without anything extra on Slackware, and forum member ruario has made it super easy to install and keep Chrome up-to-date with his latest-chrome.sh script.

But seriously, as Richard Cranium stated, you should get rid of Flash. It is going to be completely EOL next year as even Adobe wants it to die. Flash is the new IE6 and it should die as quick a death as humanly possible.

Unfortunately there is one site that I visit that uses flash still, and while I am thinking along with bassmadrigal that youtube no longer uses flash, did you:

While that probably wont help youtube, I have always had to do that to get flash working correctly.

Okay well my Model-T is still kicking some how because I just used that script and although it DOES INSTALL CHROME [yeaa - altruism I guess] it does not show the URL, google search or any website for that matter but just stays on the default google search page home screen. SOOOO has anyone experienced this?

I mean how could I make it so that HTML5 is enabled on Firefox by divine right and logic as one would infer?

If you just want to watch youtube videos you could consider youtube-dl which will download the videos so they can be viewed without a browser. You can also combine this with mpv with lua support to stream the videos directly from the command line.

Well I am not doing that lol - How do I enable HTML5 like should it should already be?

HTML5 is already enabled, but the browser doesn't have support for many video formats out of the box, probably due to licensing/patent issues. Did you try my suggestion of installing ffmpeg and/or gst-libav?

That sounds like the default homepage for Chrome. What happens when you type in an address up in the top or in the searchbox in the middle of the page? I've been using that script for years and never had any problems with the resulting package. And I'm using it on 14.2 right now.

Have you updated your installation and specifically Firefox?

Just to clear up any confusions, YouTube moved exclusively to HTML5 several years ago.

Nothing happens, it just stands there and looks at me stupid.

Have you tried uninstalling Flash?

You can try and check Chrome Logs to see if there's anything obvious preventing this from working.

Just to see, did you do a full or partial install?

We need more information.

What version (and architecture) of slackware? Did you do a full install? What was excluded if not?
What version of Firefox are you trying to use?
System specifications?

Between 14.2 and -current Firefox, be it the package included or rurario's script for the latest play YouTube without issue on any machine I've tried.

As stated Flash is dead, it's not even worth installing it. I have a few .swfs I like to play sometimes but I use the Adobe Flash stand alone dev player so that doesn't use a web browser.

https://www.youtube.com/html5

Make sure you have the codecs from SlackBuilds or Alien as well, so you can watch non youtube videos as well.