@Azuza - Most audio visual jobs involve the same over all duties the article mentioned. The main differences between working as an employee and an independent contractor are in pay, benefits and flexibility.
Usually contractors get paid a lot more per hour than the employees do. However, independent contractors generally don't get benefits such as health insurance. Even though hours for employee AV technicians aren't constant they are usually more regular than for independent contractors who have to continually find places to contract with. That being said, a contractor always has more flexibility. The employee must work the hours the company sets out but the contractor always has the option of saying "no thank you" to a job.
Both options can be good ones depending on your needs and lifestyle.