If you keep getting "HELLO, YOU EITHER HAVE JAVASCRIPT TURNED OFF OR AN
OLD VERSION OF ADOBE'S FLASH PLAYER....GET THE LATEST FLASH PLAYER":
don't bother downloading and re-installing the latest Flash over and over and over again.
You will get absolutely nowhere doing that, because that is only adding to the problem.
There can really be only 3 possibilities:
1) something is wrong with YouTube
2) something is wrong with your cache
3) something is wrong with your Flash
1) YOUTUBE:
Your problem may fix itself within a couple hours, or by the
next day, because YouTube often "shuts down" a bunch of
their own servers every single day without warning anybody,
in order to update all kinds of stuff. During those occasions,
it's really YouTube's data transmissions of "Java" or "Flash"
that are poor -- not your reception of it.
2) CACHE:
If the following day your YouTube is still stuck and showing
you those awful "JavaScript" and "Flash Player" messages,
it's possible that your sub-directories of "temporary internet
files" and "cache" memory are full, and can't take anymore.
This typically results in videos being totally unable to buffer
and make it onto your computer screen.
"Temporary internet files" are 1000s of tiny bits of websites
permanently put on your computer's hard-drive. They'll stay
there forever and ever, gradually plugging up your computer
much like hair slowly clogs a sink drain, until you get rid of
them once and for all (or at least everytime things go awry).
Because your computer now has such little space in which
to "cache" a video, YouTube will mistakenly think that your
JavaScript is off or that your Flash player (unable to absorb
any more videos) is old -- meaning Flash 7 or older.
The solution to all that is to exit YouTube (but not your web
browser), then clear your "cache" of all its "TIFs", "cookies"
and "history". (See below.) After that, shutdown and reboot.
3) FLASH:
Nothing about watching YouTube has really changed in the
past 2 years. (Technically, you could still even use Flash 8
if you wanted to.) It looks like the newest Flash players are
causing many YouTubers a whole lot of grief, especially all
8 variations of version 10.
It's absolutely nuts that there's 10.0.525, 10.1.218, 10.2.26,
10.2.54, 10.12.10, 10.12.36, 10.15.3 and 10.22.87. Usually
most updates are good for only 1 thing:...software conflicts.
I have never strayed away from 9.47, and there are a bunch
of "flashers" who still live by 9.45. Think of those 2 Flashes
like Windows XP compared to Vista. Please have a look at
the "Asker's" response to this other "Best Answer" of mine:
https://answersrip.com/question/index?qid=20081125075929AABZpVS
If that seems interesting to you, here is the appropriate link:
http://www.oldapps.com/flash_player.php?old_flash_player=14
Note 1: if you've got Google Web Accelerator or something
similar to it...dump it, burn it, trash it, disable it, uninstall it,
-- do everything you can to get rid of it. GWA conflicts with
YouTube. Clicking "Don't Accelerate This Website" will not
help you whatsoever. Also, most "Messenger" applications
have a way of mucking up YouTube.
Note 2: longer videos may require "Flash" and "Shockwave"
in order to play smooth. Other than that, avoid all the sales
pitches that some Yahooers may be shilling, because they
are really disguised salespeople & peddlers. Their answers
have nothing to do with your question, and their wares may
actually worsen your problem. Besides, what kind of idiotic
answer is "Despite the fact you can't even watch or access
videos, buy our downloader." [my paraphrase]
Note 3: a very odd fix that once worked for me was altering
the URL from "www.youtube.com" to simply "youtube.com"
(or you could even try "ca.youtube.com").
Note 4: there's always the strange possibility that you may
have gone through the whole process of downloading Flash,
BUT DID YOU ACTUALLY INSTALL IT? If you have Firefox,
did you "enable" the Flash "add-on"?
I hope that my information proves to be quite helpful to you.
Internet Explorer 6:
→ Tools → Internet Options
→ Delete Cookies → OK
→ Delete Files → OK
→ Clear History → Yes
→ OK
Internet Explorer 7:
→ Tools → Internet Options → Delete...
→ Delete files → Yes
→ Delete cookies → OK
→ Delete history → OK
→ Close (browsing history window)
→ OK
Mozilla Firefox
→ Tools → Clear Private Data
[x] Browsing History
[x] Download History
[x] Saved Form and Search History
[x] Cache
[x] Cookies
→ Clear Private Data Now
Apple Safari 3:
→ Edit → Preferences
→ Security (tab) → Show Cookies
→ Remove All → Done
after that:
→ Safari → Empty Cache → Empty
after that:
→ History → Clear History