As others have said seems risky for the laptop if something were to go wrong with your X8. And the wall wart we talked about in your other thread is was 5 volts, .5 amps, nice healthy charge rate for you battery.
Your computer if usb 2.0 would also be 5 volts .5 amps. If its usb 3.0 it could supply as much as 5 amps. 5 amps would be bad for your battery, charge rate way too high, best case shorten the battery's life, worst case watch the video again.
Now most devices today have the ability to regulate incoming power. Just like your smart phone it only draws the power it can handle. I don't have a manual for your X8 but i would assume the X8's chip would throttle/regulate the incoming potential of 5 amps, just like a smart phone does, to something like .5 to 1 amp. Still why risk your laptop to use it as a very expensive battery charger.