why i cannot play and playback some videos on youtube at random time of the video?

[859]

for example a 5 minute video... whenever i click the video on its time bar, the video starts to play again from beginning or 0.00 minute.
if i want to play the video from minute 3.00, its impossible for me now, it goes back to 0.00.
this happens to me from yesterday after a "500 error", but im not sure the problem is related to the error or not.
but some videos that i found to have the problem yesterday, didn't have the problem since today.

i'm using windows 8.

the same videos i tried on other pc windows 7, i have no problem as above.

i have tried both sign in and sign out youtube, mozila firefox, google chrome, reinstall windows.... the problem occurs in all situation and i didn't find solution.

is this a problem related to my windows 8 pc?
how to solve the problem

i need to know the cause and the solution for this problem, thank you.
for example this video https://www.youtube.com/watch?v=g2drZ3lysIE
but i can watch this video on this page without the problems above.

[inukjuak90]

"Error 500" is a server/cookie issue.   Chances are YouTube is having some
"internal" connection issues with their servers.   However, one thing you can
definitely do is clear your Cache + Cookies + History, then shutdown/reboot.

Mozilla Firefox:
→  Tools  →  Options  →  Privacy ('key')  →  Clear Now
[x] Browsing History
[x] Cache
[x] Cookies
[x] Offline Website Data
[x] Authenticated Sessions
→  Clear Private Data Now

Google Chrome:
→  ≡  or wrench  → Tools  →  Clear browsing data
→  the beginning of time ▼
[x] Clear browsing history
[x] Empty the cache
[x] Delete cookies and other site and plug-in data
→  Clear browsing data

Don't forget to totally shutdown+reboot afterwards.

:-)