I am not a tax pro so don't take my answer to the auditor or your CPA....
It is my understanding that you can write off the percentage of a thing you used for business. So if you are using your internet once a week for business and you use it once a week the equal amount for personal stuff, then you could write off 50%. Or if you were using it once a week for 30 minutes for business and every day 8 hours a day for games and videos and .......... I doubt you could justify writing it off.
But thats just my opinion.........
