The fight wasn't stopped at 8, it was stopped at 10. You hear the announcer counting, he says 7 then he misses a second in between because he began shouting, he then finished where he left off by saying 8.
However, the referee is clearly still counting. What you hear is not what the refere is doing.
REF vs WuH(what u hear)
Ref .6.....7....8.....9......waves off
wuh 6.....7....Foreman gets up to a knee! 8.....It's over!
If you watch the clock on the bottom right, you'll notice a second and a half clearly goes by while he is talking, and then you hear 8. The count is wrong, the referee had already gotten to 10. It was just the announcer failing to count properly.