Yeah there's.... something to be said about backing up your own stuff - I've seen too many people who claim "omg they wiped x and y off the net and that was my only copy!!!"
Why is it your only copy?
Never delete anything. Ever. I mean hell - I have like 4 copies of COH on ONE computer. I have redundancies aplenty.
So... if you find a video you like? Copy it. Set aside a partition on your drive and just log what you don't want to lose. I have several friends' geocities sites on my computer, when they announced they were closing I went to sites I knew hadn't been updated but played roles in my life over the years, and I got all the pages I could from them. (of course, 3 other more or less official archive sites sprouted up overnight also archiving them, lol, geocities closing 'to save space on the internet' caused a bigger problem than it solved...)
Anyway: archive away. But never rely on online sources to keep YOUR work 'safe' because it simply isn't. Make multiple copies of everything, because hard drives fail. Burn to disk.