Having them is a major plus. Adds that extra safer way of web browsing. Like google searching/images. I use the WOT extension to highlight unsafe pages therefor no accidentally clicking them. Not that I've ever had problems in the past but it's handy to have and flag up anything potential. Better to have a warning than none at all.
All these years using extensions I couldn't live without them. Especially for Youtube since I've ditched Flash. Nearly viewing everything in HTML5 with no performance problems.
What is the latest version of Safari for 10.4.11? did it end at 4.0.3? no hidden extension part under Safari Preferences>Advanced>show developer menu, extensions hidden away in there at all?
I wont go into detail about the extensions if you don't have the option to use them.
But look at the options if you could use them and what they do.
http://www.pimpmysafari.com/pages/safari-extensions/
https://extensions.apple.com/
Ah, thank you for that; I'm not really up on plug-ins! In fact, I was watching a YouTube vid as I was following your suggestion, and was surprised to see it suddenly go dead! I've just done a quick bit of Googling and I gather plug-ins enable one to receive visual/audio information - like videos, PDFs, etc.
Yes, everything thats plugin related can take out Safari if a problem occurs. You can see which is installed under the help menu with plugins enabled. You can't view them when plugins are disabled.
Since I've disabled plugins sometime ago and got rid of Flash, Safari has been a much smoother and stable experience. It's rare for it to crash unless it's a load of animated gifs, that still seems to be plagued on Lion.
According to Youtube, if you're registered...
http://www.youtube.com/html5 it says you can get html5.
"Apple Safari (h.264, version 4+)"
If you are registered and can get it and have Perian installed, I'd recommend disabling Perian for a better Youtube experience. Or it will make playback choppy as it's loading.
Which has got me thinking: sometimes I've found Safari crashes at the end of a YouTube vid - do you think that's plug-in related?
Most likely because as I said since plugins with the supplied applications no longer get updated, there will still be buggy code. IMDb.com was terrible for beachballing crashing Safari.
Your issue with Youtube would have been with the Flash plugin. It's a write off since the beginning. PDF's you can manually download anyway. Copy link and paste in the downloads window, then manually, scan/view whatever you intend to do with it.