I read about these reports often...
http://forums.techguy.org/multimedia/671802-youtube-500-internal-server-error.ht ml
http://www.worldlawdirect.com/forum/off-topic-messages/41075-youtube-google-serv er-down-07-14-10-500-internal-server-error.html
http://www.google.com/support/forum/p/youtube/thread?tid=5a6d067942a4e123&hl=en
Still, if you think it might be on your end, I think you should get Applejack...
http://www.versiontracker.com/dyn/moreinfo/macosx/19596
After installing, reboot holding down CMD+s, (+s), then when the DOS like prompt shows, type in...
applejack AUTO
Then let it do all 5 of it's things.
At least it'll eliminate some questions if it doesn't fix it.
The 6 things it does are...
Correct any Disk problems.
Repair Permissions.
Clear out Cache Files.
Repair/check several plist files.
Dump the VM files for a fresh start.
Trash old Log files.
First reboot will be slower, sometimes 2 or 3 restarts will be required for full benefit... my guess is files relying upon other files relying upon other files! 🙂
Disconnect the USB cable from any UPS so the system doesn't shut down in the middle of the process.
Then... Try putting these numbers in Network>TCP/IP>DNS Servers, for the Interface you connect with...
208.67.222.222
208.67.220.220
Then Apply
DNS Servers are a bit like Phone books where you look up a name and it gives you the phone number, in our case, you put in apple.com and it comes back with 17.149.160.49 behind the scenes. 🙂
These Servers have been patched to guard against DNS poisoning, and are faster/more reliable than most ISP's DNS Servers.