Here’s how: Towards the bottom of section 5 (“UNAUTHORIZED ACCESS AND ACTIVITIES”), this language appears:
If you access craigslist or copy, display, distribute, perform or create derivative works from craigslist webpages or other CL intellectual property in violation of the TOU or for purposes inconsistent with the TOU, your access, copying, display, distribution, performance or derivative work is unauthorized. Circumvention of any technological restriction or security measure on craigslist or any provision of the TOU that restricts content, conduct, accounts or access is expressly prohibited. For purposes of this paragraph, you agree that cached copies of craigslist webpages on your computer or computer server constitute “copies” under the Copyright Act, 17 U.S.C. § 101. For purposes of this paragraph, you further agree that CAPTCHAs and telephone verification are “technological measures” that effectively control access to copyright-protected components and rights of CL pursuant to 17 U.S.C. § 1201.
The part that I’ve bolded there basically seems to be saying that, by using Craigslist, you’re agreeing that merely looking at the pages (which necessarily means that copies of the pages are made in your computer’s RAM, and often means that copies are stored on your hard drive) is subjecting you to a lawsuit for copyright infringement, unless you obey all of the terms in that lengthy agreement.