You can check for problems with current Shockwave Flash plugin versions and hardware acceleration in Firefox and try this:

• make sure you have the latest Flash version:
  http://www.adobe.com/special/products/flashplayer/fp_distribution3.html
• check for updates for your graphics drive drivers
  https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration
• disable protected mode in the Flash plugin (Windows Vista and later)
  https://support.mozilla.org/kb/adobe-flash-protected-mode-firefox
• disable hardware acceleration in the Flash plugin
  https://helpx.adobe.com/flash-player/kb/video-playback-issues.html
• disable hardware acceleration in Firefox
  https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

See also:

• http://kb.mozillazine.org/Flash#Troubleshooting

Thanks cor-el for the post.

• I had already updated Flash but I have double-checked, latest version in use

• I have checked, drivers up-to-date

• I have disabled protection mode although slightly confused on the point re:

This article does not apply to the new 64-bit Firefox for Windows 64-bit operating systems. Mozilla has its own 'NPAPI plugin sandbox' security feature, which is enabled by default on Windows 64-bit Firefox

I am using W7 64 bit but there was a box re protected mode so I have unticked this

• I ran a check on a video that didn't work before and at this stage there was no improvement

• I unchecked hardware acceleration in Flash – checked the video, still no joy

• I unchecked hardware acceleration in Firefox - now it seems ok

So, this seems like a result and I am very grateful for your help.

However, being used to IE where things just seem to work this all seems a tad "suck it and see". I much prefer Firefox but this makes me wonder whether for the non-techie folk, FF is too unreliable?

Anyway, thanks again.

22.5.16: FURTHER PROBLEMS SEE NEXT POST

Now post the above changes I discover that if I click on some webpages (nothing to do with anything video-related) Firefox disappears from my screen for several seconds!

I cannot believe that on a nearly new Dell laptop Firefox can cause so many problems.

I am migrating to Linux eventually (at present I am dual-booting on another laptop) so really want to make Firefox work but can understand why people stick with Windows and IE!

Anyone in the Firefox community who can help? Thanks!

I guess I am talking to myself but hope springs eternal.

In frustration at the above I refreshed Firefox and now some pages open as some form of coding; a Mozilla forum page opens with a list as follows:

   Ask a question
   Contributor Tools
       Quickstart Guide
       News & Resources
       Contributor Forums
       Article Discussions
       Knowledge Base Dashboard
       Localization Metrics
       Recent Revisions
       Help on Twitter
       Support Forum Home
       Support Forum Metrics
       Media Gallery
       Advanced Search
       KPI Dashboard
       Community Hub
   Upplander
       View Profile
       My Questions
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   English

instead of a normal web page.

Some pages also open with the message:

Your connection is not secure. The owner of xyz has configured their web site improperly. To protect your information from being stolen, Firefox has not connected to this web site.

Meanwhile the slow page opening continues.

None of this happens in IE or Opera.

There is nothing wrong with the computer but clearly there is some issue on my computer when using FF. I have turned off the antivirus (Eset) but this makes no difference.

At this point I would stress:

1) I accept that FF is a free browser and 2) I accept that nobody is compelled to answer but ...

I would have thought that Mozilla kept an eye on unanswered questions and want to see something like this resolved. Clearly not.

So .. my suggestion to anyone is give yourself a break and don't use Firefox. Opera seems to work fine and I will be able to use it on Linux as I migrate.

Meanwhile this confirm's my wife's opinion that I am starting to talk to myself.

Over and out.