It is mandatory to declare that income, T4 slip or not. I file it through form T2125. Although not that much can be deducted for [phone/internet/etc.] expenses, they usually do cover all the taxes. Once you're used to it the extra paperwork on your tax report takes about 2 minutes/year.

Clients are paying for a report as well as footage... It's much easier to read/manage/copy/classify/archive/understand a professional summary than to watch an amateur video over and over and over again. We're paid for that.