Although the original DBZ script in Japan had Vegeta yell "It's over 8000!" when Nappa asked what Goku's power level was, FUNimation changed it to 9000 due to a translation error and that famous line became an internet meme most of us wish would just go away. But here's a treat, the original JP voice actor for Japan (Ryō Horikawa) shouted "It's over 9000!" at this convention. It is very interesting to hear the original voice over Brian Drummond or Chris Saban say this infamous line, check out the video below!
Also, maybe he knows more about the upcoming DBZ movie? Hopefully someone asked him a question regarding it at this anime convention!