There are two separate things: a plugin from Oracle called Java, which is used for some games and scientific/academic applets on websites, and JavaScript, which is probably used on every website in the world and which Firefox handles internally.

If one site says that JavaScript is not enabled or is not working, it could be that this is a misdiagnosis. For example, some sites try to start up the Flash player and assume it is a script problem if that doesn't work. Another possible explanation is that you have an add-on which is blocking one of the site's scripts (for example, from a different server).

According to the following page, the site uses the Flash and DivX plugins: http://www.watchfreemovies.ch/how_to_watch_movies.html

I have the latest Adobe Flashplayer on my laptop and I'm still not able to watch movies from www.letmewatchthis.com

Can you capture a screen shot of the error message? This article has tips on how to do it. Please blur or delete anything personal or confidential in the image before posting (below the reply box, you'll see the Browse button to attach the image file).

How do I create a screenshot of my problem?

I don't know how to send you a screen shot

Here is the screen shot of the messege I continue to get.

As I could see on your screenshot, You have to enable java AND download VauDix plugin. BUT BEVARE see

http://www.onlinethreatalerts.com/article/2013/8/29/how-to-remove-adware-vaudix-plugin-codec-c-/

"/ The Vaudix plugin installation file was scanned and the following threats found:

   ADWARE/InstallRex.Gen
   Win32:InstalleRex-Z [PUP]
   Adware.Downware.1442
   Win32/InstalleRex.K
   HEUR:Downloader.Win32.AdLoad.u
   PUP.Optional.Installrex
   Rising Trojan.InstallRex!562A
   AdWare.Agent

/"

Does that mean I have a virus on my laptop now?

I can't tell. This article is from 2013-08-29 and there are some newer ones to. So I don't know if it was /is just their installation file from the Vaudix homepage. Test your laptop with some good malware-scanners. The link in ..onlinethreatalerts.com/..... is outdated, but there are others.

If you get a lot of ads when your surfing then you probably got it.

Try a different streaming host like Putlocker as it uses Flash and not Java plugin.

The ads popup as they tend to do on (free) streaming or download sites. Does not mean you are infected as I get popups even though I use Linux.

The install Vaudix plugin message is not a required thing as it is just a trick to get less experienced people to download it.

Everytime I go to www.letmewatchthis.com, I always select Putlocker, but still doesn't allow me to watch a movie.

I have McAfee and it's always scanning for malware or viruses.

Any sort of websites, especially those engaged in illegal movie downloads like this, that asks you to install a special plugin should immediately be treated with intense suspicion. I strongly suggest you use the tools Troubleshoot Firefox issues caused by malware to check that your computer isn't infected, and then use legal methods to watch movies going forward (Netflix, Google Play, etc.)