«Why should be used proxies at parsing of search engines? I do not understand, why anonymity at queries in search engine »
The fact that the program is making a huge number of simultaneous queries to the search engines, so over time they block requests from the current IP as consider it as a DDOS-attack (although it is not). In this situation, the use of anonymous proxy is required.
«Is it demo of Hrefer available?»
Unfortunately, no. But Hrefer is included to the XRumer package for free.