Youtube by default needs Flash, but you can change settings if your browser supports it.
- In https://support.google.com/youtube/answer/91449?hl=en you expand "never play HD" to go to the settings page, and see what you can do there. But you need a google account to use it.
- http://www.youtube.com/html5 has a button to switch from your 'standard player' to 'view with html5. But I'm afraid that IE8 in XP (higher is not possible) doesn't run html5.
But since Adobe still issues security updates for Flash, I shouldn't care so much about it.
Kees
Following my recent received email update from Cnet regarding continuing with Windows XP, I have uninstalled Java, Adobe Reader & Flash. Replaced them with Noscript, Foxit & installed Kaspersky as recommended. I now find I have problems viewing/downloading any videos on Youtube & Facebook etc.. Is there an alternative to Flash that I can install to overcome this?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic