The description of Full-text Search for Sql Server 2008 R2 says about the Filter Daemon Host Process:

"The filter daemon host is a process that is started by the Full-Text Engine. It runs the following full-text search components, which are responsible for accessing, filtering, and word breaking data from tables, as well as for word breaking and stemming the query input."

http://technet.microsoft.com/en-us/library/ms142541(v=sql.105).aspx

It is the same for Sql Server 2008 and 2012.