I did some heavy video processing and downloading and editing for an entire month, and let my computer run almost 24 hours a day. How much kW.h could i have possibly used? should i be worried about my electric bill?
Don't think you have to worry, it probably does not consume more than 1 KW per day if you leave it on and use it at Max loads.
So, 30 KW a month, that shouldn't be more than S5-10 dependable on the price of 1 KW.
Just googled, seems I was right, it is more or less 30 Watt peak, without charging battery.
Ok, the charger can provide up to 60 Watts. At full load you are usually very close to that, but lets say 50 Watts. Over 24 hours that makes 1.2 kWh, so 36 kWh per month.
However, the charger consumes more energy than it provides (it gets warm!). Lets say for simplicity that it consumes 100W to provide the 60W to the laptop. Then you end up with 2.4 kWh per day or roughly 70 kWh per month.