How to rid roots from sewer pipes

[Angela Smith]

We are having a problem with slow drains.  Had a camera put through the plumbing and discovered roots in the clay sewer pipe.  The plumber quoted $900 to jet it out, or $3500 to dig up and replace the pipe.

I see there are chemical root treatment options for this that is much cheaper.  My question is, does is work?  Does it cause damage to clay pipes?